Weak signal after I switched from BT

[#1]

Hi I please need your help; I switched recently from BT to Plusnet and the signal is really poor. We live in ground floor flat and the router is in the front room (near the road). I have shed in the garden that I use for work and when I had a BT, I had one of those boosters disc there . The signal was very strong. Now i can even get it in the next room let alone in the garden. 
Q; should I move router to middle of the flat? Would that help? Can I get a booster ( and which one)? Can I use bt disk booster? 
what else? 
I’m not great with technology so I need an idiot proof help. 
ThNk you 

[#2]

Any hardwired wireless access point will improve your coverage. 

[#3]

I assume that when you switched to Plusnet you started using the Hub 2 router they sent ?, If so there is nothing stopping you from using your previous BT Hub if you still have it, Plusnet allow this, although they don't support them when it comes to fixing faults,

There are guides in the router section of the forums on how to get the BT Hubs working with your Plusnet service, It might be worth doing that, see if you get a better wi-fi signal working with your booster going back to the Bt Hub,

[#4]

Thank you for replying. Yes I have loooooooong wire around along the fence that I can plug it into. I think the disc thingy was plugged into it previously.
Thank you

[#5]

Thank you that’s really helpful. I’ll have a look at the posts you suggested and try.

[#6]

Moderator's note:
Thread moved from Full Fibre to My Router