Canon 600EX II-RT drops link- HELP!

[Phillyphoto]

Scenarios I have tried: 

Using Canon Transmitter ST-E3-RT as the master and (2) 600 EX II-RTs as slaves.

Using A 600EX as master and B 600EX as slave.

Using B 600EX as master and A 600EX as slave. 

I get the same result of the slave dropping link. The time varies. Sometimes it drops link in 4 mins, sometimes 10mins, sometimes 20 or more minutes. The only way to relink them is by turning everything off and back on.

All channels are the same. Yes, I have scanned for the best connection as well as every other channel and AUTO.

All IDs are the same. 

Not near a wifi-router or airport, I'm in a row home in Philadelphia. 

Using NiMh rechargeables and using freshly charged batteries for every test. Batteries are about 2 years old. 

I have spoken to 2 Canon service reps and neither of them has any idea what the problem is. I really don't have the money to spend on sending everything in for "repair". 

Any help is greatly appreciated, thanks!

[MMCphoto86]

I've been using my new flashes successfully for a couple months and last night the links dropped again and I couldn't get them to connect for longer than a minute. I suspect there's an interference like other people have mentioned; there were a ton of wireless lights and sound equipment around. Going to try Yongnuo flashes instead. I'd try the Godox system w the 600s but I'm reading reviews on B&H that they don't work with the Canon R6 camera.  

[tseager]

I was considering Godox as well. What issues specifically with the R6?

[RoxannaRouleau]

I have been having the exact same issue. I have a canon 5d mark iv, st-e3-rt, 430ex iii-RT, and a 600EX ii-RT. The exact issues you described happen with my transmitter and flashes. It also happens when I remove the transmitter and use my 600EX ii-RT on camera as a master and use the 430EX III-RT as a slave. Either way, the slave(s) always disconnect and stop linking. I have searched channels to find strongest connection. It happened while I was working 2 different weddings and also at my home when I was trying to figure out what is going on. Did anyone ever get any type of answers of assistance? 

[MMCphoto86]

Good news, it looks like it was a firmware update issue that has been resolved. I just ordered some Yongnuo flashes but might test the Godox transmitter/receivers too.

[MMCphoto86]

Nope - it seems to be an ongoing struggle. Canon insisted nothing was wrong with my flashes even though I showed the tech a video of the links dropping. I bought all new 600 EX RT-ii units only to have them drop again this past weekend. The only thing I can determine is that it's a new wireless interference of some kind like others have suggested in this thread; I realized it now tends to happen whenever I'm indoors. I just bought the Yongnuo 600ex equivalent like @steppy suggested and might try going the transceiver/receiver route with Godox products if the Yongnuo flashes don't work. 

[RoxannaRouleau]

I would like to add that I just brought out my old yongnuo 600ex-ii rt and linked them up with my canon transmitter and flashes. Both of the canon flashes dropped the link and the yongnuo stayed linked with the transmitter. So frustrating this is happening. My canons are not that old either.

[MMCphoto86]

Agreed, super frustrating! I shoot weddings too and receptions have been extra stressful due to this issue. Is there a reason why you stopped shooting with the Yongnuo flashes?

[RoxannaRouleau]

My yongnuo could not keep up with wedding receptions. It would over heat so quickly and stop working. The batteries would be extremely hot too. So it was just unreliable. My canons can fire for the whole day and not over heat. They have been great for family formals and receptions until just recently when the link drops. After reading this thread I feel like calling canon will be pointless.

[Steppy]

I have a LOT of wifi and home automation running over 2.4GHz and nothing interferes with the 600EX-RTs except the Apple Home Pods. I've pulled out the Home Pods for the last few days and today, by pure coincidence, I tested with a great deal of this stuff actually between the transmitter and slaves with no link problems at all. It's probably jus bad luck if you find a situation with a device that interferes, but you have no control of the situation and on a paying job would be a real pain. It's also unlikely that anyone at Canon will be able to reproduce the issue unless they also have such a rogue device in the building.

After receiving my Yongnuo flash I read reports that the light has a slight magenta cast. I haven't checked this out yet, but if it does prove to be a problem I'm thinking it might be correctable with a 1/8 green gel or similar.

[tseager]

A firmware issue with the Canon or other flashes mentioned here? Did it resolve the issue for you? Do you have a link you can share? Thanks!