NAS Web Wallet returns "Error: Unknown error" whenever I try to send a transaction

[roy-runner]

I successfully generate the Raw and Signed Transaction codes, as well as the QR, but when I click to send the transaction, the above-mentioned error message occurs.

I've tried several browsers: Firefox, Brave, Safari and even Edge.

It's interesting to note that the error message appears before in Firefox, Brave and Edge, e.g., when I try to unlock the wallet or input "To Address".

What might I be doing wrong?