I’m absolutely in the market for a new image viewer. One with a sensible gallery / (sub-) folder view.

I’ll try nomacs out today.

I don’t know what your previous setup was, but given that running resolved fixes your DNS issues, run:

ln -sf ../run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

This will point programs that use /etc/resolved.conf during DNS resolution to the local DNS server provided by systemd-resolved.

Then, enable resolved so that it is started when you reboot:

systemctl enable systemd-resolved.service

Finally, start the service so that it is available immediately:

systemctl start systemd-resolved.service

You will want it run those with the required permissions, e. g. via sudo.