compatibility problem, you need to check the network type and band they supported, not so sure about the SIM card of EE, but you can check that of tplink here:...

Any English version?

never used wake on lan... you'd better contact tplink, if you get any info from us, please share with us, thanks!

mac OS 10.13? I have the same problem, so I've contacted TP-LINK, new controller utility would be released soon

5G led is still on? you may try to change 5G channel, try different web browser or different devices if you still cannot save it

where did you download the new firmware? you'd better download it from your region's website, choose correct hardware version first, since your router is version 1, only firmwares under version 1 can...