I moved the save file to the client. and swap the client and the server.
but it has the same problem.
the server(the client before) can play with the single game but the client (the server before) cannot join the game
it stops at the loading screen with the fulled loading bar over 2mins
Client
i7-2600k @4.2Ghz
10GB RAM
Game on HDD
Server
Ryzen7 3700X @3.6Ghz (PBO)
32GB RAM
Game on SSD (Reading 3500MB/s, Wrting 2500MB/s)