I’ve done a quick test with openrtsp, available via Entware (probably a docker package exists too).
opkg update
opkg install openrtsp
Example with a test stream from RTSP Stream Test | Wowza
mkdir /shares/Public/test
openRTSP -4 -F /shares/Public/test/ -P 10 rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov
