Phantasy Star Online 2 launched on April 14 of this year on Xbox One, and although there's a few quality of life upgrades on my wish list, things were mostly stable. The PC edition that arrived just this past week on May 27: not so much.
After a number of folks had issues even logging in, much less keeping the Windows 10 build (which is the only PC option right now) stable, Sega has acknowledged the problems and opened up a landing site for players. The page instructs users on what to do for numerous error codes, from downloading the game from the Windows Store to sign-in bugs to patch problems.
A lot of the strife seems to stem from the Widows Store. While Microsoft was instrumental in bringing this classic west, they also need to be on top of the impending fixes so people can jump back in as soon as possible. You can find those instructions below.
Then there's the stuttering in-game, once you conquer all of those error codes. Sega is working directly with the development team to implement fixes for that on June 10.
Windows 10 Issue Report [PSO2]