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!

[Steppy]

Interesting… I had tried them outside the house, about 10 yards into the garden, away from all Wi-Fi, but I still had the same issue. Today I took them across the field, around 100 yards away, and the link remained good! It turns out the limit in my case is around 15-20 yards from my house. That’s at about the full range of my Wi-Fi as far as my laptop is concerned.

I’ve been collecting 600EX-RT units for a future project (fortunately I stopped at 3) and tested each as I received them, inside and outside the house, with no obvious problems. I can’t imagine having changed anything significant since the last tests. I also use 3 550EXs with Phottix Laso receivers and they work wonderfully.

I recently added a Canon ST-E3-RT to the constellation, so I now have a total of 7 RT units. This would put my system into the range of the issue reported by p4pictures of 7 or more units, although the error description is rather obscure. However, this may be unrelated if others have the same issue with an EL-1 and a ST-E3_RT Ver. 2, and tseager with only 600EX II units, i.e. no Ver 1 units involved at all.

Yesterday I ordered a Yongnuo YN600EX-RT II flash (cost me the same new as a second hand Canon 600EX) and so far it’s working exactly as expected. I originally wanted to go the Canon route for quality, compatibility and reliability reasons, but that’s not looking to be a very good choice at the moment.

I’d like to bring the units back into the house and systematically turn off all Wi-Fi devices to see if I can identify any offending sources, but that will have to wait until tomorrow as my wife won’t appreciate me interrupting her Zoom meeting!

Thanks for all your responses

Step

[Steppy]

After several hours of experimentation I can confirm that the source of interference in my particular constallation were 2 Apple HomePod minis. If I disconnect power to both devices the 600EX-RT slaves remain connected. I've successfully tested for about an hour so far without issue. If I connect power to either HomePod the slaves lose connection within a couple of minutes. Both HomePods behave the same. I have not identified any other problems with any other Wi-Fi devices being affected by these HomePods.

Quite possibly these HomePods are generating more noise than other WiFi devices, and I'm guessing the noise immunity of the Canon flashes is perhaps marginal. The Phottix receivers and the Yongnuo flash do not appear to be affected at all.

While the Yongnuo flashes look virtually identical to the Canon units, you have to look very closely to tell them apart, there are very slight differences in build quality. They even have more features than the Canon units, but I really need them so haven't tested them out yet. Obviously it's early days, but if I were looking for a reliable flash system then I certainly wouldn't eliminate 3rd party products (anymore).

Thanks silverdoggg for your suggestion

Step

[Steppy]

I've continued my testing and the results may (or may not 😉 ) be of interest to others.

All Canon units are the first versions.

Firstly, I tested with all 15 channels and a wide range of different IDs but found no difference at all.

Master: ST-E3-RT
Slaves: 3x 600EX-RT
Slaves lose connection, master LED remains GREEN, apparently indicating that the connection loss has not been detected.
Connection can only be restored after recycling power on BOTH master and slaves (as halocastle reported it may be possible to just cycle the RF link but I've not tested this). Sequence is unimportant (slaves before master or master before slaves).

Master: ST-E3-RT
Slaves: 3x 600EX-RT + 1x YONGNUO YN600EX-RT II
Canon slaves lose connection. Yongnuo slave remains connected and continues to flash when triggered by master.
When YN600EX-RT II turned off and on again it fails to reconnect.

Master: ST-E3-RT
Slaves: 3x 600EX-RT + 1x YONGNUO YN600EX-RT II
Master initially turned OFF. All 4 slaves turned ON. Wait ca. 10 minutes.
Turn on master.
Canon slaves do not connect.
Yongnuo slave connects and flashes when triggered by master. 

Master: ST-E3-RT
Slaves: 3x 600EX-RT + 1x YONGNUO YN600EX-RT II
Master turned ON. All 4 slaves turned OFF. Wait ca. 10 minutes.
Turn ON all 4 slaves.
NONE of the slaves connect to the master.

Master: ST-E3-RT
Slaves: 3x 600EX-RT + 1x YONGNUO YN600EX-RT II + 4x Phottix Laso TTL Receivers
All Canon slaves lose the connection to the master. The Yongnuo and Phottix slaves remain connected and trigger when fired by the master.
If I only use 2 of the Phottix devices initially they remain connected as above, but if I turn on the remaining Phottix devices after the Canon slaves have been dropped they cannot connect to the master. 

Previous tests indicate the same behaviour when using a Canon 600EX-RT as a master. This is to be expected because the ST-E3-RT is probably just a simplified version of the flash, and probably uses very similar firmware and electronics for the link functionality.

Master: YONGNUO YN600EX-RT II
Slaves: 3x 600EX-RT + 4x Phottix Laso TTL Receivers
All Canon slaves lose the connection to the Yongnuo master.
Phottix slaves remain connected and trigger when fired by the Yongnuo master.
The Canon slaves reconnect to the master after cycling the power to the slaves only, with no further action required on the Yongnuo master.
If I only use 2 of the Phottix devices initially they remain connected as above, if I turn on the remaining Phottix devices after the Canon slaves have been dropped they RECONNECT to the Yongnuo master. 

[Mannies17]

Same exact scenario for my home. If I take it away to a park they’re totally fine. 5 out of the 20 weddings I had this year produced reception interference inside the church or reception hall. For sure is something per location. The wireless routers???

[Steppy]

Every WiFi device both transmits and receives as do the flash master AND slave units. In my case I've identified the source of the interference to be 2 Apple HomePod Minis. If I pull the power on these two the flashes remain connected for as long as I've monitored them.

[JimOsdale]

It's quite the problem for Canon at this point. I have two of the brand new EL-1 flashes, and one of the older 600EX-RT flashes, and they all have a problem staying connected. Upon further investigation, it's not the ST-E3-RT with the problem because I turned off this transmitter, and turned it back on several times to see if the LEDs were still green, and within about 10 minutes, one of the EL-1s dropped the connection, so how can this be the transmitter problem? Based on my tests, it's the flashes that are dropping the connection, and we all know it's RF interference, could it be the new WiFi-6 wireless access points around the house and commercial venues? There are other posts that suggest Apple HomePods are the issue, but these items are not in my house, so I cannot confirm or deny these are the conflicting hardware. I do have the new WiFi-6 access points from UniFi as my "MESH" Wi-Fi system in the house.

I made some other tests by purchasing the "sock" that covers the flash and sort of shields it from the RF interference, but this causes more grief because you are essentially now limiting the ability for the transmitters to communicate to the flashes. These are not the solution either, as the link was still dropping. Ugg...

So I did some other tests, and I bought the ($80 USD) Godox transmitter X-Pro II C, and purchased two of the ($40 USD) Godox X1RC receivers for mounting to the Canon EL-1 flashes. Using this configuration, I NEVER lost the link from the Godox transmitter to the Godox receivers, EVER. I let this run for hours, made several tests, used my Canon R5 in different configurations, manual mode, ETTL, and the connection stayed solid, I never lost the link to the flashes.

That being said, there are plenty of posts throughout the Canon forums where this is a huge problem for Canon, and you hear suggestions from Canon support: "Try changing the batteries". Are you kidding me, that is ridiculous, they have nothing else to suggest because deep down they know that interference with all of the "Internet of Things" on WiFi-6, and the 2.4 GHZ band is full of traffic. So why does the Godox (Chinese made) hardware stay connected?

Unfortunately, this means a few more dollars for additional hardware, more AA batteries, but at least the connection is NEVER dropped, and I do not have to power cycle the Canon flash and Canon transmitter. The other downside to Godox transmitters & receivers, you don't get all of the features that Canon has to offer, but in reality, do you really need to have the flash at less than 1/128 power? I say this because the Canon transmitter and EL-1 flash can be set to 1/8192 power, and the Godox can only be set to as low as 1/128 power, which is not a big deal in my opinion. You do however get some pretty cool features in the Godox transmitter, you can turn off any single flash by double tapping one of the 5 group buttons, a useful feature that is super fast.

Deep down, I really think Canon has a problem that may not even be fixable though firmware, it's most likely the frequency that Canon uses that is conflicting with nearby RF devices. In my opinion, why Canon does not reconnect automatically instead of power cycling the hardware is beyond me.

[garmanmd]

I have found a workaround that is back to the future.  When the RT doesn't work I can use my old ST-E2 transmitter to trigger the new flashes in the optical mode.  Of course has all the limitation of the old setup which is why we all moved to RT, but at least the flashes will work for basic function.  It does seem there is no fix since it's a basic design problem that conflicts with something that is new in the wifi world.  Pretty disappointing Canon won't acknowledge it, and that we all spent thousands of $ on equip that no longer works.

[tseager]

Disappointing that the EL-1 has the same issue. The problem is the frequency and protocol. I verified this using a combination of third party flashes, strobes and transmitters that use the Canon protocol. Nothing works on the Canon protocol, unless removed from interference. The Godox and Westcott units work on their own protocols, likely due to lessons learned or freewheeling with the spectrum.

[garmanmd]

I think your suspicion about WIFI6 might be correct.  The only change in my house was replacing the router with the newest version which has wifi6.  I could always go backwards at home, but can't control all the public spaces.  That makes sense in why some public spaces are just fine (probably have older technology), and others are not.

[Nick55]

I have had the same router here for two years in location with issue of “Link Drop”. 
Nothing  new added here.