I literally stopped playing a few months after release because I got fed up with No[630] Error, but it looks like it's still going strong. Not everyone has stable internet.
From my testing back then, I determined that I have a chance to have this error when my internet loses packets. Losing a packet every so often isn't uncommon in certain cities due to poor maintenance, disruption and congestion. Though there were a good amount of players back then that claimed that they encounter the No[630] Error without losing any packets.
I already gave feedbacks to address this issue back then to no avail. They can increase the delay for internet loss before booting the player with the error, or they can have a system to reconnect when connection is lost. From the games I tested, PSO2 has the shortest time it takes before it "disconnects" giving the No[630] Error. It takes approximately 15 seconds of "disconnection" before the No[630] Error pops up.
There are multiple games that implemented solutions that addresses this issue. If anyone played MS2 at launch, they would most likely also had the same problem. MS2 addressed this problem by adding automatic reconnection. I don't know if BDO had it on launch, but their solution is also automatic reconnection.