Issue running cmk-agent-ctl.exe" register with error Request failed with code 401 Unauthorized:

I get this with no port, or port 800 and 8001

Attempting to register at checkmk.redacted.com:8000/cmk. Server certificate details:

[2022-06-01 18:07:25.153483 +10:00] ERROR [cmk_agent_ctl] src\main.rs:29: the handshake failed: error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl\record\ssl3_record.c:332:

Caused by:
0: error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl\record\ssl3_record.c:332:
1: error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl\record\ssl3_record.c:332: