Thank you for the reply. As 1.5.1 is currently working fine at my location, I will wait to see if other users give more feedback. Good to know the downgrade is possible though.

I have currently M9Plus(2.0) 1.5.1 Build 20210126 Rel. 59387 No problems experienced. I work from home and I am depending on this router is working ok. Now I am offered an upgrade to 1.5.6 Build...

@Vibaek78 I am running firmware 1.5.1 with my 3xM9+ (2.0) devices for a year, and I do not experience instability, I am running it for months without any reboots. My M9+ is running in router mode, my...

@brzd I would like to bump this question myself. I just set up my own server with <name>.tplinkdns.com and it works fine, but is not accessible from some company computers who require HTTPS So is it...

@TP-Link Does a feature list describing the changes from 1.5 to 1.6 exist somewhere? I now have 3xM9+ with 1.5.1 Build 20210126 Rel. 59387, and it is working fine. Before performing any upgrade it...

@AV-Guy Yes it is correct, I do exactly this. I use wired backhaul to second M9+ via switch. My third M9+ used wireless backhaul, so there is a lot of flexibility.