Hy folks- does anyone here use Proton Mail on 2degrees fibre?

Just trying to help a friend who suddenly lost access last night.

It works fine on his phone using mobile data or hot spotting laptop to phone, but not laptop on the home wifi network.

Have flushed DNS and updated DNS settings to manually use Google, but still no go.

I have told him to take it back to Proton Mail with that troubleshooting to help, but wondering if anyone here in the same situation and whether you were able to fix it.

Contacting 2degrees could be tricky as he is not the account holder- he piggybacks of his landlord's wifi upstairs. Also means we probably can't/shouldn't access the router.

TIA.