There are multiple thing to know and to check according your internet config.
I give you a short checklist:
Check on your local PC, that you server is running on the port you expect (Simpli try to connect on the same PC with "localhost" as target)
Check if you have running any Firewalls on your local PC, that could block your port
you can try to ...
well i would try power cycling or restart the router if that does not work try updates if that does not work either check if your router and modem are plugged in, if nothing works try nintendo support or refer to the instruction booklet.
You can't access any of the modes that allow you to play with other players if you don't have a PlayStation Plus subscription.
It doesn't matter if is via Xbox Live, PSN, LAN or a Dedicated Server, you need PS+ to play even if you are alone in that server.
I figured it out for java, you need to put in your local ip address in the server.properties text file in ip address, so like (192.168.1.2) I do not know why this is but this allows people to connect to your public IP, to join your own server however you need to type in your local IP
So to join on your machine, use local ip, for someone to join you, give ...
This is not a definitive answer, but my experience is also that there is no way to continue. The platform does not detect it automatically, and there are no controls in-game to signal these conditions and re-sync manually.
(Ticket to Ride is not the only platform that suffers from this problem, and it is frustrating.)