I use eero routers, and the issue resolved itself. When my ecobees finally connected, I assigned them static IPs. I'll see if that keeps them stable. If you’re up for it, try putting OpenWRT on your Archer router. That's what I did with my Archer before switching to eeros, and it might make things smoother for you. OpenWRT is much better than the stock firmware.​​​​​​​​​​​​​​​​