After struggling for a while with 1.6.x firmware for Deco M9 Plus, and believe me I thought my main router was causing this problems or the outdoor cable and I tried everything (reset, new cables etc), but after months of using 1.6.x firmware and then downgraded to 1.5.6 it just solved everything, Deco units are working perfectly now. 

1.6.x firmware is just not stable for everything, while it include a lot of features I really want such as ( Schedule reboot, Satellite source, preferred WiFi band for each device.. etc) but unfortunately it doesn't seems like a stable firmware for various problems that just keep happening. 

Examples:

- Ping is not stable. 

- Sometimes it just take a while for loading pages/apps. 

- Schedule reboot makes more problems? Rebooting it manually and it just works fine again lol, I really don't know what is happening. 

Summary:

There's a lot of missing features in 1.5.6 firmware and I really like 1.6.x firmware, but if you're having bad experience with your units after upgrading to 1.6.x firmware just downgrade to 1.5.6 and everything will work again as expected, since we will not get the 1.7.x firmware anytime soon and the future firmware is unknown for this device I'll just stick with 1.5.6.

Maybe I'm the only one having these issues with M9 Plus 1.6.x firmware? I don't know, share your experience to help others.