Persistent disconnection issue WOW51900319

I get disconnected from the game (WoW Classic) with the following error: WOW51900319. I play in EU on EU Servers
I have the disconnection issue with WoW, only. On other game or program are affected.

I have now tried the following:

  • reinstalled wow classic and battle. net
  • updated drivers
  • used different chars and realms
  • ran the game with and without addons
  • port forwarded
  • priotized the computer in the routers settings
  • Flush DNS, reset TCP/IP
  • switched between LAN and WIFI
  • Different routers and DSL cables
  • had my ISP check connection stability
  • VPN and mobile hotspot tests
  • used a VPN
  • I have had all surrounding programs off and turned of most other devices
  • I had a security software on the old pc and disabled it. On my new computer I just use windows defender (Windows 11)
  • WoW Classic and Battle.net were added to the exceptions in the firewall
  • changed coumputer in the mean time (old: Intel CPU/Nvidia GPU; new: AMD CPU/AMD GPU)(setup from scratch)

Having the same issue here on retail, Will be able to log in but when I enter different zones like instances / hubs everyone else will freeze and I am not able to interact with any buttons, Dont even disconnect from the server I have to tab out to close wow down. All characters are effected.