diff --git a/react-web/.env.production b/react-web/.env.production
index bdf7549f..56afd081 100644
--- a/react-web/.env.production
+++ b/react-web/.env.production
@@ -1 +1,2 @@
-REACT_APP_BASE_URL="https://testing.dapps.iog.io/"
\ No newline at end of file
+REACT_APP_BASE_URL="https://testing.dapps.iog.io/"
+REACT_APP_WALLET_NETWORK="1"
\ No newline at end of file
diff --git a/react-web/src/app/App.scss b/react-web/src/app/App.scss
index 5423910b..4dfff414 100644
--- a/react-web/src/app/App.scss
+++ b/react-web/src/app/App.scss
@@ -9,4 +9,20 @@ header button {
 section > svg.spinner {
     top: 100px;
     left: 50%;
+}
+
+
+#contentWrapper {
+    margin: 0 auto;
+    padding: 40px;
+    color: #2d333a;
+    @media (max-width: 768px) {
+      & {
+        padding: 0;
+      }
+    }
+}
+
+#globalBanners {
+    padding: 10px 40px;
 }
\ No newline at end of file
diff --git a/react-web/src/app/App.tsx b/react-web/src/app/App.tsx
index 5277c1fe..bb6a2d10 100644
--- a/react-web/src/app/App.tsx
+++ b/react-web/src/app/App.tsx
@@ -1,12 +1,14 @@
-import React, { lazy, Suspense } from "react";
+import React, { lazy, memo, Suspense } from "react";
 import { Routes, Route, Outlet } from "react-router-dom";
 import { BASE_URL } from "constants/route";
+import Alert from '@mui/material/Alert';
 
 import "./App.scss";
 import Header from "components/Header/Header";
 import PrivateRoutes from "components/PrivateRoutes/PrivateRoutes";
 import NotFound from "components/NotFound/NotFound";
 import Loader from "components/Loader/Loader";
+import { useAppSelector } from "store/store";
 
 const Certification = lazy(() => import("../pages/certification/Certification"));
 const MaintenancePage = lazy(() => import("../pages/maintenance/Maintenance"));
@@ -19,9 +21,32 @@ const Pricing = lazy(() => import("../pages/pricing/Pricing"));
 
 
 const PageLayout = () => {
+  const { network } = useAppSelector((state) => state.auth);
+
+  // const networkNames:{[x:string]:string} = {
+  //   '0': 'Testnet',
+  //   '1': 'Mainnet'
+  // }
+
+  const Banner = memo(() => {
+    const networkEnvVar: any = process.env.REACT_APP_WALLET_NETWORK
+
+    return (<>
+      {network !== null && network !== 1 ? 
+        // always show Info if not in Mainnet
+        <Alert severity="info" style={{marginBottom: '10px'}}>Your connected wallet is not in Mainnet.</Alert> : null}
+        {/* if not in Mainnet and app-wallet not Mainnet (i.e. in Testnet), show Warning to connect to Preprod. */}
+      {network !== null && network !== 1 && networkEnvVar !== '1' ? 
+        <Alert severity="warning">Being in a test network, please make sure you are connected to wallet in <strong>Preprod</strong> to avail services without any issues.</Alert> : null}
+    </>)
+  })
+
   return (
     <>
       <Header />
+      <section id="globalBanners">
+        <Banner />
+      </section>
       {/* Load page content here */}
       <section data-testid="contentWrapper" id="contentWrapper">
         <Suspense fallback={<Loader />}>
diff --git a/react-web/src/components/ConnectWallet/ConnectWallet.scss b/react-web/src/components/ConnectWallet/ConnectWallet.scss
index eef6a234..4c2ca698 100644
--- a/react-web/src/components/ConnectWallet/ConnectWallet.scss
+++ b/react-web/src/components/ConnectWallet/ConnectWallet.scss
@@ -60,4 +60,7 @@
     span {
         padding: 2px 16px;
     }
+}
+.error {
+    color: red;
 }
\ No newline at end of file
diff --git a/react-web/src/components/ConnectWallet/ConnectWallet.tsx b/react-web/src/components/ConnectWallet/ConnectWallet.tsx
index 4d40a805..b9477583 100644
--- a/react-web/src/components/ConnectWallet/ConnectWallet.tsx
+++ b/react-web/src/components/ConnectWallet/ConnectWallet.tsx
@@ -1,11 +1,12 @@
 import React, { useEffect, useState, useCallback } from "react";
 import { Address } from "@emurgo/cardano-serialization-lib-browser";
 import { useAppDispatch } from "store/store";
-import { getProfileDetails } from "store/slices/auth.slice";
+import { getProfileDetails, setNetwork } from "store/slices/auth.slice";
 
 import Modal from "components/Modal/Modal";
 import Button from "components/Button/Button";
 import Loader from "components/Loader/Loader";
+import Toast from "components/Toast/Toast";
 
 import './ConnectWallet.scss';
 
@@ -24,6 +25,7 @@ const ConnectWallet = () => {
     const [walletName, setWalletName] = useState("")
     const [address, setAddress] = useState("")
     const [isOpen, setIsOpen] = useState(false)
+    const [errorToast, setErrorToast] = useState<{display: boolean; statusText?: string; message?: string;}>({display: false});
     const [walletLoading, setWalletLoading] = useState(false)
 
     const openConnectWalletModal = useCallback(() => setIsOpen(true),[])
@@ -34,17 +36,27 @@ const ConnectWallet = () => {
         try {
             setWalletLoading(true)
             const enabledWallet = await CardanoNS[walletName].enable();
-            setWallet(enabledWallet)
-            setWalletName(walletName)
-            if (enabledWallet) {
-                const response = await enabledWallet.getChangeAddress()
-                setAddress(Address.from_bytes(Buffer.from(response, "hex")).to_bech32())
-            }
+            enabledWallet.getNetworkId().then(async (data: number) => {
+                dispatch(setNetwork(data))
+                setWallet(enabledWallet)
+                setWalletName(walletName)
+                if (enabledWallet) {
+                    const response = await enabledWallet.getChangeAddress()
+                    setAddress(Address.from_bytes(Buffer.from(response, "hex")).to_bech32())
+                }
+            })
         } catch (e) { handleError(e); }
     }
 
-    const handleError = (err: any) => {
-        console.log(err)
+    const handleError = (error: any) => {
+        if (error.info) {
+            setErrorToast({display: true, message: error.info})
+        } else if (error.response) {
+          setErrorToast({display: true, statusText: error.response.statusText, message: error.response.data || undefined})
+        } else {
+          setErrorToast({display: true})
+        }
+        setTimeout(() => { setErrorToast({display: false}) }, 3000)
     }
 
     useEffect(() => {
@@ -88,8 +100,16 @@ const ConnectWallet = () => {
                         })
                     }
                     { walletLoading ? <Loader /> : null}
+                    {
+                        (errorToast && errorToast.display) ? (<span className="error">{errorToast.message}</span>): null
+                    }
                 </div>
             </Modal>
+            {/* {(errorToast && errorToast.display) ? (
+                ((errorToast.message && errorToast.statusText) ? 
+                <Toast message={errorToast.message} title={errorToast.statusText}/> :
+                <Toast />))
+            : null} */}
         </>
     )
 }
diff --git a/react-web/src/components/Header/Header.tsx b/react-web/src/components/Header/Header.tsx
index 8067f6eb..d74f7028 100644
--- a/react-web/src/components/Header/Header.tsx
+++ b/react-web/src/components/Header/Header.tsx
@@ -2,7 +2,7 @@ import React, { useEffect, useState, memo, useCallback } from "react";
 import { useNavigate, Link } from "react-router-dom";
 import { Address } from "@emurgo/cardano-serialization-lib-browser";
 import { useAppDispatch, useAppSelector } from "store/store";
-import { logout, getProfileDetails } from "store/slices/auth.slice";
+import { logout, getProfileDetails, setNetwork } from "store/slices/auth.slice";
 import "./Header.scss";
 
 import AvatarDropDown from "components/AvatarDropdown/AvatarDropdown";
@@ -10,10 +10,11 @@ import ConnectWallet from "components/ConnectWallet/ConnectWallet";
 import { useDelayedApi } from "hooks/useDelayedApi";
 
 const Header = () => {
-  const { isLoggedIn, address, wallet } = useAppSelector((state) => state.auth);
+  const { isLoggedIn, address, wallet, network } = useAppSelector((state) => state.auth);
   const dispatch = useAppDispatch();
   const [isActive, setIsActive] = useState(false);
   const [pollForAddress, setPollForAddress] = useState(false);
+  const [pollForNetwork, setPollForNetwork] = useState(false);
   const navigate = useNavigate();
 
   useEffect(() => {
@@ -25,6 +26,9 @@ const Header = () => {
         try {
           const enabledWallet = await window.cardano[walletNameCache].enable()
           dispatch(getProfileDetails({"address": addressCache, "wallet": enabledWallet, "walletName": walletNameCache}))
+          enabledWallet.getNetworkId().then(async (data: number) => { console.log('new network -', data)
+            dispatch(setNetwork(data))
+          })
         } catch(e) {
           console.log(e)
         }
@@ -42,7 +46,15 @@ const Header = () => {
 
   useEffect(() => {
     setPollForAddress(wallet && address && isLoggedIn);
-  }, [wallet, address, isLoggedIn]);
+    setPollForNetwork(wallet && address && isLoggedIn && network !== null)
+  }, [wallet, address, isLoggedIn, network]);
+
+  const forceUserLogout = () => {
+    // account/network has been changed. Force logout the user
+    setPollForAddress(false);
+    setPollForNetwork(false)
+    dispatch(logout());
+  }
 
   useDelayedApi(
     async () => {
@@ -53,17 +65,32 @@ const Header = () => {
         newAddress = Address.from_bytes(Buffer.from(response, "hex")).to_bech32()
       }
       if (newAddress && address !== newAddress) {
-        // account has been changed. Force logout the user
-        dispatch(logout());
-        setPollForAddress(false);
+        forceUserLogout()
       } else {
         setPollForAddress(true);
       }
     },
-    3 * 1000,
+    1 * 1000,
     pollForAddress
   );
 
+  useDelayedApi(
+    async() => {
+      setPollForNetwork(false)
+      wallet.getNetworkId().then((id: number) => {
+        // Preview/Preprod/Testnet are all 0. Switching among them cannot be distinguished.
+        // But, switching to-and-fro Mainnet is triggered
+        if (id !== network) {
+          forceUserLogout();
+        } else {
+          setPollForNetwork(true)
+        }
+      })
+    },
+    1 * 1000,
+    pollForNetwork
+  )
+
   const hasCachedAddress = () => {
     return (!localStorage.getItem('address')?.length || !localStorage.getItem('walletName')?.length)
   }
diff --git a/react-web/src/index.scss b/react-web/src/index.scss
index ea7caa0e..438a5d58 100644
--- a/react-web/src/index.scss
+++ b/react-web/src/index.scss
@@ -15,17 +15,6 @@ body {
   // position: relative;
 }
 
-#contentWrapper {
-  margin: 0 auto;
-  padding: 40px;
-  color: #2d333a;
-  @media (max-width: 768px) {
-    & {
-      padding: 0;
-    }
-  }
-}
-
 input {
   font-family: monospace, -apple-system, BlinkMacSystemFont, "Segoe UI",
     "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans",
diff --git a/react-web/src/pages/certification/Certification.scss b/react-web/src/pages/certification/Certification.scss
index 6138fa1e..7502e4f5 100644
--- a/react-web/src/pages/certification/Certification.scss
+++ b/react-web/src/pages/certification/Certification.scss
@@ -87,17 +87,20 @@
 }
 
 #resultContainer {
-
+  button.back-btn {
+    background: transparent;
+    cursor: pointer;
+    border: none;
+    img {
+      width: "30px";
+      padding: "10px";
+    }
+  }
   header {
     display: flex;
     justify-content: space-between;
     flex-wrap: wrap;
     gap: 15px;
-    .back-btn {
-      background: transparent;
-      cursor: pointer;
-      border: none;
-    }
     &>div {
       display: flex;
       flex-wrap: wrap;
diff --git a/react-web/src/pages/certification/Certification.tsx b/react-web/src/pages/certification/Certification.tsx
index 52aa274c..1b449d8a 100644
--- a/react-web/src/pages/certification/Certification.tsx
+++ b/react-web/src/pages/certification/Certification.tsx
@@ -292,24 +292,21 @@ const Certification = () => {
       {formSubmitted && (
         <>
           <div id="resultContainer">
+            {runStatus !== "finished" ? (
+              <button
+                className="back-btn"
+                onClick={(e) => {
+                  resetStates();
+                }}
+              >
+                {" "}
+                <img
+                  src="images/back.png"
+                  alt="back_btn"
+                />
+              </button>
+            ) : null}
             <header>
-              {runStatus === "finished" ? (
-                <button
-                  className="back-btn"
-                  onClick={(e) => {
-                    resetStates();
-                  }}
-                >
-                  {" "}
-                  <img
-                    src="images/back.png"
-                    alt="back_btn"
-                    style={{ width: "30px", padding: "10px" }}
-                  />
-                </button>
-              ) : (
-                ""
-              )}
               <h2
                 id="breadcrumb"
                 style={{alignSelf:"center"}}
diff --git a/react-web/src/store/slices/auth.slice.ts b/react-web/src/store/slices/auth.slice.ts
index 33b97e4b..12073e21 100644
--- a/react-web/src/store/slices/auth.slice.ts
+++ b/react-web/src/store/slices/auth.slice.ts
@@ -9,6 +9,7 @@ interface AuthState {
   wallet: any;
   userDetails: IUserProfile;
   loading: boolean;
+  network: number | null;
 }
 
 // Define the initial state using that type
@@ -17,7 +18,8 @@ const initialState: AuthState = {
   address: '',
   wallet: null,
   userDetails: {dapp: null},
-  loading: false
+  loading: false,
+  network: null
 };
 
 const clearLSCache = () => {
@@ -25,11 +27,11 @@ const clearLSCache = () => {
   localStorage.removeItem('walletName')
 }
 
-export const getProfileDetails: any = createAsyncThunk("getProfileDetails", async (data: any, { }) => {
-    localStorage.setItem('address', data.address) 
-    const response = await fetchData.get("/profile/current", data)
-    // FOR MOCK - const response = await fetchData.get(data.url || 'static/data/current-profile.json', data)
-    return response.data
+export const getProfileDetails: any = createAsyncThunk("getProfileDetails", async (data: any, { rejectWithValue }) => {
+  localStorage.setItem('address', data.address) 
+  const response = await fetchData.get("/profile/current", data)
+  // FOR MOCK - const response = await fetchData.get(data.url || 'static/data/current-profile.json', data)
+  return response.data
 })
 
 export const authSlice = createSlice({
@@ -41,9 +43,13 @@ export const authSlice = createSlice({
       clearLSCache();
     },
     logout: (state) => {
-      clearLSCache()
+      clearLSCache();
+      state.loading = false;
       return initialState
     },
+    setNetwork: (state, actions) => {
+      state.network = actions.payload
+    }
   },
   extraReducers: (builder) => {
     builder.addCase(getProfileDetails.pending, (state) => {state.loading = true;})
@@ -70,6 +76,6 @@ export const authSlice = createSlice({
 });
 
 
-export const { logout, clearCache } = authSlice.actions;
+export const { logout, clearCache, setNetwork } = authSlice.actions;
 
 export default authSlice.reducer;