First method.

1. Press WIN+R and run regedt32
2. Go to
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/TerminalServer
3. Create file MaxOutstandingConnections (DWORD) with 1000000
4. Restart

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Second method.

1. Run command line as Administrator and run command:
REG ADD "HKLMSYSTEMCurrentControlSetControlTerminal Server" /v MaxOutstandingConnections /t REG_DWORD /d 1000000
2. Restart.