Weak signal on Fibre router

Fibre signal is poor on both of my security cameras and my central heating control system.  The latter goes from no signal to one dot, seldom even reaching the first curved bar.

TBH I don't think that the new router is any better than the old one.

I see no reason why I should have to pay £85 for an extender especially if a significnat improvement cannot be guaranteed.

Any ideas welcome

Thanks

Tony