I also have exactly the same problem too, same port, IP and everything. This issue is so annoying, I can't even download Skyrim 2020 Parallax. For me it happened around the 20th of February
A few days ago SKSE was working perfectly. Now for some reason, when I click on PLAY on the Steam Library. It just turns me into "In-Game" then "Online" SKSE Is broken... I even tried to reinstall it with Steam and used "Verify Integrity of game cache" Something is definitely going on