No hair left

Hi all you knowledgeable peeps

I have registered on the forum specifically to request your help.

My wifi is all over the place. I am downstairs, the router (SR101) is upstairs, probably 10 yards away, but not in direct line of sight. I cant connect to it directly at the moment, but can connect through a netgear WN2000RPT booster.

I use the booster as my house is quite long, and there is a PC in the back bedroom. The SKY router signal doesn't reach the back room.

There are a number of devices connected:
My desktop PC (via booster)
2 x kids desktop PC's (1 via booster, 1 via sky router)
1 x PS4 (via sky router)

My PC wifi speeds are all over the place. I have used Ookla. One test can give me 4mb, the next a minute later 14mb. I disconnect, the kids PC's disconnect, the PS4 disconnects, we have limited access, no access.......aaarrgghhhhh

I am normally quite good at sorting this stuff out, but am at my wits end.

Personally I reckon the router packing up. I am out of my 12 month period so apparently need to by a replacement if needed...haha. At the moment, BT is looking good, maybe even plusnet.....

Can anyone give me any suggestions as to why the wifi is so variable?

I have tried the usual, channel hopping, moving the router (limited due to power cable length).

Any pointers would be appreciated.

Thx
Guy

recent wifi speed tests