canon operates in 2.4 gigahertz channels that is operated by dynamic router and 5G smartphones mores in the past 5 years.
Canon would either have to allow the receivers in the flash to DYNAMICLY reset the receiver without you having to power cycle them (this would have to be a change on the actual flash unites, not just the transmitter), or operate in the less used 330-400mhz bandwidth that is far less used today... this is what pocket wizards use.
dunno what's up canon's ass for not acting on this.
I've done a lot of experimentation with my flashes and have also opened a case on the issue (no resolution). The problem occurs sender to flash, flash to flash, sporadically typically in 2-3mins in my environment.
I don't think the problem has anything to do with "interference". We have all kinds of devices coexisting on the frequencies successfully. I suspect that the receiver unit itself picks up something that it thinks it needs to listen to and crashes. Can't bring it back up until you power cycle the flash(es) or transmitter. Normally the receiver has the ability instantly reconnect if it loses connection (i.e. you turn off the transmitter), but when the receiver crashes it can no longer resync.
This is something you think could be fixed with a firmware update; I asked Canon on the case if there was any way to get diagnostic data out of the flash unit or transmitter but got no answer on that.
I think if there was a firmware fix for this they would have done it already (Assuming they can update flash firmware at all), otherwise maybe they're using an embedded receiver that cannot be updated.
Can't see why they would continue to let this problem exist in the new flashes though.
I'm using EL-5 / 2x 600EX-RTs, and the ST-E-something for the Intelligent hotshoe on the R3/R6m2. I'm thankful my 600ex's can use optical, and have a 580ex to trigger optical if there is wifi around.
Have contemplated getting an RF spectrum analyzer to see what's going, also.