The IP address of the machine you're connecting to has probably changed. If the previous had a DHCP lease, that wouldn't migrate with the new router.
Go on your Windows machine and open up a command prompt. Type in "ipconfig" (no quotes) and validate the machines IP address. It should start with 192 or 10 most likely. Maybe 172.
If it's the same as it used to be, that's not the issue. But my bet is that it's changed.
I mean, seems fair? It's not like we haven't seen large scale cyber operations carried out in the past, and not a single one has ever been deemed to rise to being an act of war.
Unless you're killing power to hospitals or something, cyber effects seem to be fair play in the modern world stage.
You think Russias gonna declare war on NATO because they have some IT systems destroyed, or a bunch of records stolen or deleted or whatever? I really completely fail to imagine anything short of the "killing power to a hospital" example that would cause an escalation, and honestly, I'm not even sure that would.
Russia is happy to do it to other countries. Turnabout seems fair play to me. Especially since they're doing it while actively committing genocide on a neighboring country.