Thanks for the response @Desmond Richardsonthese are the answers to your questions:
a) We are in the seventh season
b) The date when this roughly started happening around December 14th
c) No connections have changed, all consoles have stayed in their same locations.
Also, I got the nations list wrong if that matters. The correct loaded nations are Brazil, Denmark, England, France, Germany, Greece, Italy, Portugal, Scotland, and Spain. The issue also seems to not be save specific, because none of us could join an older save or a new one together.
Let me know if you have any following questions are updates on the problem being fixed, I'm very eager to return.
UPDATE: As of January 1st at 3:25 AM myself and my two friends were able to all load into the save, I'm not entirely sure as to what made it work though. We uninstalled and reinstalled two or three days ago and when we tried to join that day it still didn't let us in. No idea why we were able to get in now and not entirely sure we'll be able to get in tomorrow but we will see with time.