My MR400 work perfect But when I installed Google Nest mini and Chromecast the devices didn't connect to internet. They connected to the wifi but not possible to cast. After googling around and came to this thread thru Reddit. I turned off 4G and connected to only 3G. Everything worked. When turning on 4g again the Google Home devices disconnected. 

Firmware Version:  1.6.0 0.9.1 v0001.0 Build 181112 Rel.65058n

Hardware Version: Archer MR400 v1 00000001

I got Chilimobil as service provider on 3.

Do you got I possible solution yet?