I'm having issues with Wi-Fi backhaul seemingly blocking other traffic over WIFI.  Specifically, I have the X60 3 pack and it's setup with a typical setup, with one connected to my modem and the others using the wireless backhaul feature.  This setup generally works well.  However, I'm currently doing a cloud backup of my office computer (wired directly to one of the Deco x60 routers that is connected over wireless backhaul to the main one). This process has been ongoing for a couple weeks (I have a lot of data to backup and my upload speeds aren't amazing).

My ISP internet speed for uploading is around 12 MBps and I'm getting that backup speed on my office computer. I can see, in the Deco app, that my office x60 is showing around 12MBps upload and that the main Deco is also showing a similar upload speed when the backup software is running. However, while that upload is occuring, other devices connected only by WIFI, no matter which x60 they are connected to, can't seem to actually send/receive data over the network.  My office computer works without a hitch, but calls over WIFI through my cell phone are choppy and/or drop, all other computers in the house which are connected over WIFI to the main Deco simply won't load a webpage, Echos won't work, any gaming over WIFI won't work, etc.  These devices all show a connection to the router, it's just that things time out and are unusable.  I did some troubleshooting and if I stop the backup process on my office computer, everything returns to normal immediately.  I also got a very long ethernet cable and connected my office x60 to the main x60 by ethernet (ethernet backhaul) and, even with the backup process running, everything works normally.  Everything has been restarted multiple times.  I swapped out the actual x60 devices on the off chance one of them was having an issue, and that didn't solve anything.  So it's not my ISP, it's not the WIFI hardware in my devices, it's not the backup software. I think I've narrowed down the issue to the wireless backhaul.

This...doesn't seem normal.  12MBps shouldn't stress the x60 wireless backhaul to the exclusion of all other traffic.  That's nowhere near what these things are rated for.  I routinely play movies over my network with bitrates in the 60 to 90 MBps range over the wireless backhaul while other devices access the network without issue.  Is there some reason the cloud backup would cause this type of issue?  Is there a setting or something else that needs to be checked/unchecked?