Random disconnects and then "realmserver not active"

Hello, since around 4 days I have constant disconnects from EU cluster (mop classic). It is completely random when it happens, sometimes I can play 3 hours until it starts and sometimes WoW is completely unplayable. What happens is:

  • I disconnect from server with classic Error Code: WOW51900319
  • I go to main menu and hit reconnect, then I either can’t get past loading screen and sometimes I get into game and then instantly disconnect
  • back to main menu, error says „realm server not active“
  • I can’t reconnect even after restarting PC, router, Game producing the same error „realm server not active“ (on server status it says it is and others from my guild don’t have it)
  • after random amount of time I can get back in before the cycle continues

This is really annoying and is ruining the fun, not knowing how long before the next disconnect happens.

What I already tried (as suggested by tech support in two tickets) without it stopping:

  1. Check Firewall/Antivirus Settings
    Sometimes security programs can accidentally block Blizzard games or services. Adding exceptions for Blizzard’s executables or required ports can help.

  2. Restart Your Computer and Router/Modem
    A quick restart of your networking equipment can often clear up temporary issues. Here’s a guide to walk you through it:

  3. Disable Background Applications
    Other programs running in the background—especially those that use a lot of resources—can cause slowdowns or connectivity problems. Learn how to manage them here:

  4. Flush DNS Cache and Reset Network Configuration
    Refreshing your network settings can remove conflicts that affect your connection. Instructions are available here:

  5. Restart your computer before doing any other troubleshooting. This can resolve many program conflicts and other temporary issues

  6. If you are having trouble connecting on ONLY one character, [go here]

  7. Run the Battle.net App [repair tool

  8. [Optimize your internet connection]. Your current setup may have issues impacting gameplay

  9. Lag and disconnections are often caused by outdated or broken addons. If you use any addons, do the following:

  10. Update any addons that you use

  11. Try disabling all of your addons. Navigate in-game to Main Menu > Addons > Disable All

  12. If all else fails, fully [reset your user interface] (UI)

I don’t know how to fix it. After creating two tickets and always getting the steps above I am really done with Blizzard Support. They just copy past the things above and mark ticket as resolved. I send the logs and they don’t even want to get to the bottom of the problem.

I would really appreciate some advice.
Thank you.