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!

[eschrad]

TL/DR: I think I've found the SOLUTION.  Scroll to the end... Involves changing flash ID, and also possibly radio channel.
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I recently had this issue for the first time at an outdoor wedding I shot.  I thought it was the DJ's equipment causing interference and so I tried both Auto radio channel selection as well as manually forcing the flashes to stay on the same channel.  I still had the wireless link constantly dropping and the only solution was to turn them all off and back on again and force the re-link.  I was using an 600 EX II-RT on-camera (master), and then slaves off-camera were a 600 EX II-RT and a 430 EX III-RT.  This was my first time using all 3 flashes in this way... for years I had just used the two 600s without issue.  I could never figure out what the problem was, so I just kept thinking it was the DJ's setup.

Recently, I was shooting in my house and I was using just a 600 on-camera and a 600 off-camera and I had the same dropped link issue.  At this point, I was getting concerned because this 2-flash scenario had never failed me before.

So I started diving into my custom function settings again and reading online to see if there was something I was missing or if something had changed.  But everything seemed set right for my preferences and for this type of shooting.  I started messing with different configurations with all three flashes (changing channel selection, changing auto-sleep settings, changing order of how I turned everything on and off, etc, etc), and mostly what I ran into was this: when my on-camera flash would go to sleep and my slaves stayed on, if I woke up the camera and master flash again, the only flash that would relink to the 600 EX II-RT master was the 600 EX II-RT slave... the 430 EX III-RT would stay unlinked.  One possible solution looked to be turning off the auto-sleep function on the master, but I hated to do that because a lot of times I do shoot with one flash and I like for it to auto sleep to save battery power.  Besides... this seemed like a hack solution and didn't really get to the core issue that when the master powers off, one or both of the slaves don't relink.  

SOLUTION!!  (I think!)  After all the fiddling around and resetting things back to what they were when it didn't make a difference, the answer seems to be changing the Flash ID number (the 4-digit number shown under the radio channel setting).  Pretty sure most/all of us have never before thought to change that, not really knowing what it did, and so we've all only ever shot with our flashes on the default 0000.  Sometimes when we have had link issues, we've gone from Auto Channel to a set channel and that seems to fix things... which can be true if another shooter is using a different channel or there is in fact DJ interference.  But at home, by myself, channel interference issues didn't seem to be the source of my delinking because I could use Auto or force a channel and still lose the link to the 430 slave (and sometimes the 600 slave).  But once I changed the ID on all 3 flashes to the same number that wasn't 0000, I was able to maintain a link between ALL 3 flashes.  Even when my master went to sleep and I woke it up, both slaves relinked when only the 600 slave would relink before changing the flash ID.  I turned my master off completely and turned it back on and all 3 relinked.  I turned wireless transmission off and back on on the master and all 3 relinked.  I fired test shots and changed modes and turned flash firing off and on and a bunch of other settings and the links held.

So I thought that was it... setting flash ID had resolved it.  But then I did encounter a time where, after my master went to sleep, I lost the link to the slaves and couldn't get it back upon waking the master.  At first, I could at least get the 600s to relink to each other... but this time, neither of the slaves (600 or 430) relinked to the 600 master.  So then I went in and manually set the channel as well so that they were all the same on all 3 flashes, as well as maintaining the custom ID I set previously.  Then I left everything on and sitting for a long time.  The camera and master flash went to sleep.  The slaves reached their 1 hour auto-off time.  I woke up the camera and master 600 and then turned the slave 430 back on and it relinked instantly.  (The slave 600 had completely died.)

So I encourage everyone try changing the flash ID number (from 0000 default) and let me know if that fixes things for you too!  As for Auto Channel or manually set Channel... needs may vary depending on interference encountered.  I still have to see how this holds in a real shoot or wedding scenario, but I'm optimistic about this solution. 

[crlyhds]

Boy does this sound familiar. I did all of the above but not sure if I changed the radio ID. I'll have to try that. One thing I noticed when I had the flashes under an rf shielding blanket. My phone still showed my wifi but not any of the neighborhood. Flashes all worked as advertised. Outside the blanket I still had link issues. So, one of my neighbors has a "dirty" wifi network. Bottom line the problem is not wifi as as a whole, just some wifi. Good to know but doesn't really solve the problem.

     As a side issue, I got a request from Canon to review the community support page. I highlighted their "non response" to this issue. 

[p4pictures]

This sounds interesting, and may be why I've not experienced the issue with the dropped links like others in the forum. 

From day 1 of owning my first pair of 600EX-RT and an ST-E3-RT way back in 2012, I changed the ID from the default 0000. I once worked out that the most awkward - needs the most button presses - is to use 5555 as the ID. The reason was that I did some demonstration photo shoots on photo shows, and I wanted to reduce the chance that a person in the audience would be able to control my lights, knowingly or not. 

As all units leave the factory with the ID set to 0000, therefore by default any Speedlite or transmitter owned by anyone has a 1 in 16 chance (15 channels plus auto) of being on the same channel and ID as you, if you use ID 0000.

Add in that the earlier Speedlite 600EX-RT and ST-E3-RT units had a firmware update that needed them sent in to Canon as they were prone to dropped links and general instability when working with more than 6 or 7 devices. I ran some Speedlite workshops, and saw that issue in practice several times when I had multiple people with their transmitter switched on and a bunch of Speedlite 600EX-RT units setup for the group to control, sometimes 10 or more devices. I did send my 600EX-RT and ST-E3-RT units in to Canon for the update and never saw the link instability again. 

[RoxannaRouleau]

I wish I could say this was a solution for me. I changed the IDs as you suggested and unfortunately my link still dropped.  

[MMCphoto86]

Thank you for sharing! Unfortunately I tried changing the flash ID and always scan for the best channel - the link kept dropping. I realized it was happening at most of my indoor venues; outdoors the flashes usually stayed linked. 

I have since changed to Yongnuo-compatible flashes and they stay linked, even at all of my indoor venues. I find that the light isn't as consistent as the Canon flashes, but they get the job done. After months of troubleshooting, money spent at Canon HQ, and tons of frustration - I don't really care, so long as the flashes actually work!

[eschrad]

Shoot. I’m so sorry that idea didn’t work for you and you’ve had such a trying experience. I am hopeful this continues to hold for me, but I still need to put it to the complex test of shooting a multiple flash setup at a wedding. Keeping my fingers crossed!

[eschrad]

Darn. I thought maybe I had figured it out for everyone. I’m just hoping my perceived success holds for me the next time I put the flashes through a real use case. 

[crlyhds]

I tried changing the flash ID. Worked well in the living room where the seating is more comfortable for testing. Moved to the garage where I do most of my shooting ( water drops.) 3 flashes worked, 1 didn't. Changed the ID twice(3000) now all work as they should. Conclusion; what works in one space may not necessarily work in another. The RF environment is very variable. Distance from router, weather conditions and probably more that I am unaware of. Be flexible. If possible do a pre-check on location where you will be shooting. Even though I have things successfully setup now, tomorrow it may not. The environment changes. I hope this helps

[wwward]

I want to add another report to this chain, as I've experienced the same issue with multiple units including one new unit less than a year old.

Around the beginning of 2022 I started experiencing the same behavior that PhillyPhoto described in the thread parent. Link drops between the ST-E3-RT and one or more other 600EXII-RTs, or between one or more of any combination of the 600's.This occurs on channels that the scanner shows as maximally 'good' with various IDs, in any part of the apartment.

I've tried unplugging my wireless router to eliminate the strongest known source in the apartment, it's also the only wireless device that has been updated in my apartment around the time the problem began. Everything else has been unchanged. However, I live in a dense part of Manhattan. In 2021, I used the grouped flashes extensively in wireless mode with complete reliability.

I have to conclude that there's a new interference source, or new form of interference, that causes the RT radio to lock up. As you've all experienced, I expect, once the link light goes red, you must power-cycle every unit to bring them back up. It would have been nicer if the RT radio component accepted the interference and recovered on its own.

To validate that the issue wasn't in the flash units themselves, I placed them in the microwave oven and observed that they remained linked until one unit hit its auto-power-off limit. 

I don't see a lot of discussion about this problem on the general Internet, so I have to conclude that it's just beginning to become a problem with the RT system in some areas. 

If you've stumbled upon this thread from Google, and are experiencing the same technical problem, please chime in on this thread.

In the meantime, I'm using the classic infrared RT mode, which gets the job done, but when one pays such a premium for Canon hardware, one expects to have full functionality. Fortunately they left the infrared mode intact, else I'd have no workaround.

-Grace

[crlyhds]

One of the duties of the FCC is to prevent transmitting devices interfering with other transmitting devices. Most WIFI networks run at 2.4 Ghz. The ST-E3-RT runs at 2.405-2.475 Ghz. I'm not an RF expert but with transmitting frequencies so close together logic dictates a possibility of interference. We may have proven it to ourselves that interference is the problem but convincing anybody else, including Canon is pretty much impossible. Infrared works but I paid for a transmitter that I would like to use. Wish everyone the best of luck.