@David-TP it turned out to be having to wait 72 hours before the TV fully realised what I was trying to do. Cos apparently it takes that long for some devices. It's so weird how all the other devices...

Would changing it to AP mode do anything? Or is there a simpler method?

The Deco isn't connecting to my TV. Tried everything literally. Still isn't connecting. I have no idea what to do. It was working fine before we had a power cut. They still connect to everything else...