@A.Hamzah What about your DHCP settings, have you tried to disable the TL-WR841HP DHCP server : Post the following screenshot:

That's part of the new GUI experience. At the first encounter my decision was exactly like yours - to set the first port in the range in Internal port filed. If you want to mark the thread as solved,...

Try to set the port range in the External port field and leave the Internal port filed empty, then click on Save.

That's a good question and IMHO it should, since NAT shouldn't have anything to do with OneMesh feature, but either someone should test that in a real environment or TP-Link official confirms that.

That's not the point, because you can change the LAN IP address of C3200 to be 192.168.1.1. But the WAN IP address can't be in the same network (192.168.1.X) and vise versa. In short, configure the...

There shouldn't be any specific upgrade path. For particular devices there is a restriction for downgrading though, which is noted in the FW version description.