The protocol error indicates that the server 3389 port is open, but the 3389 port has been modified to another service port, that is, the remote terminal of the server has changed the port, you can go to the server to check whether this is the case. If 3389 is already occupied by another service application, then change the remote desktop port and use the modified port to log in!
Iis7 Remote Control:
A computer remote monitoring tool, IIS7 remote Desktop management is a professional remote desktop connection software, no installation. Easy to operate. Perfect interface design, powerful monitoring function, stable system platform, to meet the needs of users to achieve remote desktop connectivity.
1. Grouping function.
2. Import text format selection to prevent coding errors.
3, a single server to add manually.
4. Support feature search.
5. Reminder of expiration function.
6. Import server information with one click.
7. The program is automatically updated.

Reproduced in: https://my.oschina.net/u/4172372/blog/3085072