There are several community threads about this issue and yet there it has not been corrected in over 1.6 years. The only Linksys solution is to install the previous version of firmware: 1.1.8.185832
The problems I have experienced with 1.1.9.192968 include random disconnection of devices in both 2.4 GHz and 5 GHz bands, both WiFi bands shutting down without any action on my part, and low levels of throughput with wired connections.
Reverting to 1.1.8.185832, with identical settings, eliminates all of the problems and with the older firmware, the EA8500 is blazing fast and as stable as any WiFi router I have owned.
As the router works perfectly with the old firmware, I don't see any point in following the Linksys "Resolving dropping Wi-Fi connection" recommendations at https://www.linksys.com/us/support-article?articleNum=142891, which include
- Reducing Wi-Fi interference
- Customizing the Wi-Fi settings of the router
- Updating the firmware of the router
There has been lots of time to release updated firmware that works. It would be nice if Belkin / Linksys would let the community know if that is ever going to happen.