If you login to the inverter wifi (instructions on the givenergy kb site) and run the ‘scan for SSID’s’ it’ll tell you what signal strength the inverter is actually seeing.
My inverters couldn’t reliably “see” my home wifi router despite it being only 1 floor up and about 7m horizontally. I had my inverters commissioned to a powerline repeater that was in our lounge on the other side of the garage wall.
Worked quite reliably except about once a month or so the powerline would disconnect and you’d have to unplug and plug it back in again.
Personally having used powerline range extenders I wouldn’t recommend them. They are susceptible to electronic noise on the ring main. Things like USB power adapters can kill the signal, I had real trouble with some mains sockets with USB adapters in them, ended up taking them out in the end. And they can drop out for no reason at all.
In the end we bought a Mercusys AX3000 Mesh wifi 3 node system and then a couple of extra nodes, one of which is in the garage. These give us the same wifi SSID all round the house and works well. Not had any issues with dropouts. Only problem is that the givenergy wifi dongles DO NOT like 5GHz signals on the same SSID as 2.4GHz. They only work on 2.4GhZ,. You have to turn off the 5GHz, let the inverter connect, and once connected you can turn the 5GHz on and leave it connected. Perfect then