When trying to connect to an RDP host in Remote Desktop Manager macOS you get the error message: Unknown error (0x0000001C).
Solution
The workaround is to increase the default TCP acknowledgement timeout to 30 seconds (30000).
- This setting can be changed globally for all RDP entries in File - Preferences - Types - RDP - Connection.
- Or changed locally, in the entries properties Common section, by going in RDP (Microsoft Remote Desktop) - Advanced - Connection.