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.
