Thanks for the many answers to my inquiry. I have two causes so far that could trigger the problem Some have problems with connectivity to their ISP after updating the firmware All have changed the...

@Tescophil Is the controller inside the management VLAN? NO (this is a non starter, and as far as I can see has never worked if you have a TP-Link router) I my setup this works. All devices including...

@SuperUserOne Interesting. Combined with what Checko and Lurk wrote it does not seem to be a setup issue within the LAN setup but a crash loop of the router itself. Maybe the type of connection the...

The problem pattern is a bit confusing. Maybe those who have problems AND those who don't may provide the following information for all of us and TP-Link to find a solution together: Did the problem...

@mrusli I am sorry but I have to tell you that it is not the WAN side. As @Fleegle61 and I was suspecting you are pinging the routing IP of a LAN interface of the router and this has to be open to a)...

Yes it should be but if the WAN interface is inside a DMZ in a double-NAT scenario and the IPs for the networks where heavily tweaks so that .1 is not the routing IP of the network segment, this...