Changing your IP address and DNS server has multiple consequences.
Indeed. I use a software firewall that needs to be able to resolve my internal DNS addresses, so I can't set it to use the dynamically-provided ones without losing functionality. And I need to provide internal DNS in any event to client PC's. The easiest solution is therefore to hardcode the DNS server address.
Need SSH for work as well come on mweb!
SSH to Hetzner works correctly for me, so it's not completely blocked. I don't use IMAPS so I can't test that.