ENGLISH:

I have been writing to tech support, as there is no such solution to the problem anywhere. They advised me:
"What you need to do to fix this issue is the following:*Uninstall the game completely

*Delete the content in the following folder: C:\Users\"your username"\AppData\LocalLow\DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\Documents\RealmOfTheMadGod\Production
*Download the launcher from https://www.realmofthemadgod.com/ or Install the game from your Steam launcher
*Update launcher via the launcher promptAlternatively, you can also:*Uninstall the game completely
*Open regedit (WIN+R, type regedit, hit enter)
*Navigate to 'Computer\HKEY_CURRENT_USER\Software\DECA Live Operations GmbH'
*Remove all subfolders EXCEPT for the master folder itself - > DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\AppData\LocalLow\DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\Documents\RealmOfTheMadGod\Production
*Re-install the graphics drivers and restart the PC
*Download the launcher from https://www.realmofthemadgod.com/ or Install the game from your Steam launcher
*Update launcher via the launcher prompt
*Make sure you are running the game on the native resolution for the monitor (if the screen is 1920x1080, the game should be running on 1920x1080 fullscreen resolution)
*If you have multiple monitors set up, try to play the game on another different monitor
*Install the latest DirectX version available for your computer configuration (https://www.microsoft.com/en-us/download/details.aspx?id=35)
*Make sure your OS is up-to-date (you have installed all and any OS Updates)
*If you have Switchable Graphics on your computer, enter the graphics card control panel and force only the dedicated graphics card to be used for ROTMG Exalt
*Try disabling your anti-virus software and any performance boosting features like 'enhanced sync' etc.
*If you have overclocked any components on your computer, try to reset back to factory default."

It didn't help me.

And the most banal thing helped me - rebooting the router. Try it and you. Maybe you will solve this problem too. And I really hope that I helped you!

PS: If it's not difficult and I really helped you, throw praise on my MAIN account! I would be grateful! https://gtm.steamproxy.vip/id/SpoGi/

RUSSIA:

Короче ребятушки. Суть такая, списывался с тех поддержкой, так как не мог зайти на аккаунт 2 дня. Писало: "an existing connection was forcibly closed by the remote host".
Писали мне вот это, можете попробовать сделать все по порядку (Но если не поможет, то смотрите ниже)
What you need to do to fix this issue is the following:*Uninstall the game completely

*Delete the content in the following folder: C:\Users\"your username"\AppData\LocalLow\DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\Documents\RealmOfTheMadGod\Production
*Download the launcher from https://www.realmofthemadgod.com/ or Install the game from your Steam launcher
*Update launcher via the launcher promptAlternatively, you can also:*Uninstall the game completely
*Open regedit (WIN+R, type regedit, hit enter)
*Navigate to 'Computer\HKEY_CURRENT_USER\Software\DECA Live Operations GmbH'
*Remove all subfolders EXCEPT for the master folder itself - > DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\AppData\LocalLow\DECA Live Operations GmbH
*Delete the content in the following folder: C:\Users\"your username"\Documents\RealmOfTheMadGod\Production
*Re-install the graphics drivers and restart the PC
*Download the launcher from https://www.realmofthemadgod.com/ or Install the game from your Steam launcher
*Update launcher via the launcher prompt
*Make sure you are running the game on the native resolution for the monitor (if the screen is 1920x1080, the game should be running on 1920x1080 fullscreen resolution)
*If you have multiple monitors set up, try to play the game on another different monitor
*Install the latest DirectX version available for your computer configuration (https://www.microsoft.com/en-us/download/details.aspx?id=35)
*Make sure your OS is up-to-date (you have installed all and any OS Updates)
*If you have Switchable Graphics on your computer, enter the graphics card control panel and force only the dedicated graphics card to be used for ROTMG Exalt
*Try disabling your anti-virus software and any performance boosting features like 'enhanced sync' etc.
*If you have overclocked any components on your computer, try to reset back to factory default.

Если вам это не помогло, то нужно сделать самое сложное - перезагрузить роутер. Это единственное, что мне помогло и надеюсь поможет и вам!
P.S: Если не трудно и я вам действительно помог, киньте похвалу на мой ОСНОВНОЙ аккаунт! Буду признателен! https://gtm.steamproxy.vip/id/SpoGi/