I am having the same issue as explained here but my difference is that I'm not using MotionEyeOS but Ant Media Server directly.
When testing using ffplay as suggested, I am able to see the stream playing in UDP but when I force in TCP, I get the below error:
[rtsp @ 0x7fdb6707e800] Nonmatching transport in server reply=0/0
rtsp://xx.xx.xx:554/onvif1: Invalid data found when processing input
I see in the link above that there is a setting to disable TCP in MotionEyeOS but how can I disable this in Ant Media Server, please?