Add a note that your selected network must be Ethereum L1

[sbvegan]

Is your feature request related to a problem? Please describe.

The web app doesn't work unless your wallet is connected to Ethereum.

Describe the solution you'd like

I think a note on the front page should be sufficient. It could also show an invalid network selection error when users are not connected to Ethereum.

Describe alternatives you've considered

n/a

Additional context

n/a