I get the solution for GC2083. As long as [SAMPLE_COMM_VPSS_Init]-28: CVI_VPSS_CreateGrp(grp:0) failed with 0xc0068004! means Already Created according to Error Codes, the problem may lie in the process being already occupied. So I use ps and kill the two processes:
262 root /usr/local/bin/cvi_camera
263 root /usr/local/bin/RTSPtoWeb -config /etc/rtsp2web.json
After one reboot (and another kill if needed) I can smoothly connect to GC2083 and use the rstp. The rstp connection won’t get down in 5 seconds in GC2083 comared to OV5647, so use GC2083 as a preference.