Are there any solutions available for the 630 disconnection error? I have tried everything I know, including disabling IP v6, launching steam with -tcp so it'll connect via tcp and not udp. Resetting router, flushing dns cache, resetting IP stack, finally reloading PC from scratch.

None of this is making any meaningful change. The issue is strange, because it's almost as if the game is kicking me off rather than just a disconnect. Everything is going fine, then I'll get what appears to be a lag spike for 5-10 seconds, then it will recover, and about a minute later it'll disconnect me. Throughout this whole process, including up to the point I get the actual error appearing, I see alliance chat, and people moving -- just I'm not able to move, and I cant chat.

This initially was something that happened maybe once every day or two, and now it's happening every hour to me. It's making the game completely unplayable, making using bonus keys risky, etc. Are there any solutions or at least any acknowledgement whatsoever that this is happening to a lot of people?

Go to the challenge/pvp lobby and back to ship. I have yet to get ER630 doing this i did test that i do have to repeat this if i close the game.

I had this problem at PC launch and I found out it was my router causing the problem, my old router was a netgear nighthawk and apparently one of the firmware updates caused significant issues for gamers and it would frequently drop packets, games like PSO 2 literally hate that.

Are you getting Error 630 at very specific points, like joining a group with other players? Or after beating a boss/EQ? If you notice a pattern, its most likely router/modem related.