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!

[canon600]

Hi, I’m experiencing the same issue after using the 3 600ex-rt for about 5+ years. Pls let me know if u were able to find the solution. Thanks a lot 

[MMCphoto86]

I'm experiencing the exact same issue - I've been using one 600 ex ii on-camera master and two of the same models as slaves. I've had them for about 5 years. I've tried switching them around and even added a brand new speedlite to the mix. I've tried multiple bodies (an R6, a Mark III, and a Mark IV). I've had them serviced by Canon multiple times now and still they are dropping the link - Canon says they are in perfect working order. It's immensely frustrating given the amount of time I've spent going into Canon HQ - not to mention how unreliable the flashes are at a wedding! I don't know what else to do at this point. Thanks!

[tseager]

How much do they charge to service? Given your experience though, I will likely look for alternatives. 

[MMCphoto86]

Apologies for the delay! It was about $175 per flash and was unsuccessful. 

[Steppy]

Like others, I'm having exactly the same issue. It renders all my 600EXs absolutely useless. Did you (or anyone else) manage to resolve this issue?

Step

[MMCphoto86 · Accepted solution]

Sadly I couldn't resolve the issue and Canon insisted they couldn't find a problem. I ended up buying new flashes - not an ideal outcome! 

[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?

[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.

[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!