I've 2 Deco M9 Plus for my 2 different ISP. 

Both are showing sudden red light & internet connection gone.

Only after restart that will work for few times then again red light.

For testing purpose I bring Deco m5 from my home to my office. those are working fine.

Both router are physically setup within 12 inch (less than 1 meter). Specially which one also connected through wired network to another network switch that red light come very fast than from another only wifi network one.

Any solution?