This just hit me as well. core version 1.7 build 710 on NUC Linux 4.4.0-79-generic
All was working as usual earlier today. Now I’m asked to login to my core (NUC) from my mac client (been ages since I was asked to do this). Login eventually times out with a “Network Error” suggesting I check connections. I can ssh to the server box from my mac, ping out to roonlabs.com, and I’ve rebooted the server box just to be sure.