N300 connected via Ethernet yet "no internet"

Hi all I am at the end of my wit. I have a TP N300 extended and a UK Virgin Hub 5. For 6 months they were working fine together. Hub was let's say 12345abc and extender was 12345abc_ext same password, to which it set itself follow8ng a "bring close together and press wps" setup.

yesterday I realised that all Ring devices, which used the extender, were offline. I also realised thahlt Hub 5 decided to start only broadcasting 5Hz. I decided that could be the problem. I followed all of the advice to split channels and disable smart Wifi optimization in Hub 5 admin. In the process of that I renamed 2.4 channel Myinternet24 and the 5Hz channel Myinternet5band changed passwords. They are both supposed to be enabled and visible.

Nonetheless Hub 5 refuses to briadcast 2.4 signal and attempts to resync with TP Link by the old proximity + wps method yielded no progress.

I then decided to bypass this by connecting the TP Link extender via Ethernet cable. Which I know is good and working because I just plugged it out of a desktop PC. TP Link has 1/3 lights bright on now, including Ethernet, but the rest of the circle is still dim. It is still broadcasting wifi signal as 12345abc_ext and there is now onviously no internet on it.

I am pretty confident TP Link is receiving the Ethernet signal via the cable. But how do I reset its wifi settings now and make it broadcast that signal over wifi? Il

thanks for any help please keep in mind I am a middle aged lady so speak to me as you would to a toddler.