In this case to understand the issue better could you please help us with the following details.

On which device you are trying to access the modem GUI or web manger page?

Please try on different web browser to check the details

Do you have surfboard central app, if yes are you facing same issue on the surfboard central app as well?

This issue is happening when the web UI is launched from inside the Surfboard Central app on an iPhone. It appears to open safari from inside the app. I have yet to try an alternate browser. I’ll report back.

I suppose for the devices to work when viewing the web UI I 100% need to be connected via Ethernet. I want to manage some connected devices but I suppose that’s not possible on a mobile device.

Since you are unable to manage the connected devices on SBC app, I would suggest uninstalling the app and reinstall it again.

Also, please try with different mobile phone and different email address.