I've been using the Orlit RT 610 with a Canon 5D Mark IV and a Canon ST-E3-RT transmitter. The Orlit RT 610 frequently loses the link with the ST-E3-RT transmitter and I have to power everything down and restart to reestablish the link. Sometime I have to do that several times to reestablish the link.
It not only loses the link to the ST-E3-RT transmitter, the output is sometimes unpredictable, especially in ETTL mode, but sometimes even in manual flash mode. Sometimes it will start popping at full power and the only way I can get it to stop doing that is to power everything off, including the camera and ST-E3-RT transmitter.
The Orlit RT 610 will also not work in group mode and ETTL with the ST-E3-RT transmitter. The only way I can use group mode is in manual mode.
I got the V1 firmware update but that did not solve the problem. So I sent the Orlit RT 610 back and got a new one with firmware V2, and it is no better.
I wonder if this has anything to do with the fact that I am using a Canon 5D4, because my Yongnuo transmitter will not work with the 5D4? I tried my Canon 5DsR briefly yesterday and I was able to use group mode and ETTL with the ST-E3-RT transmitter.
Anyone have any info, thought's, or suggestions?