We've been playing Factorio for a few weeks now (3 friends on Steam), but as of tonight, we can no longer play together, when loading our saved game as the host it says "Failed to determine external IP address. Other players might not be able to connect." Once started, when friends search Steam friends' maps, they receive the error "Couldn't establish network communication with server". We thought it might be the usually host's router, so we took turn in trying to host the saved game (ver. 15.34), same exact issue. Other posts are referencing to a solution to simply restart servers, ours is a load game, not even sure how to start an online game. Please help, we play only once per week and now can't, it has been working for the past weeks without issues.
Any help will be apprecited.
I didn't find the right solution from the Internet.