60Mpbs from router but just 3Mpbs in next room

Sorry an old problem but neither BT nor tp-Link can help.
My BT Smart Hub router Type A is in my small office and I'm happy to receive 60Mpbs BUT in rest of the house, despite having three tp-Links scattered around I can only get 3 maybe 4Mpbs on a good day. I have tried moving the router around but there's not much choice and doesn't make much difference. BT say that "tp-Links may not be compatible with a BT set-up" which I find hard to believe. We have an ordinary brick house of which there must be millions in the UK, surely I am not alone in meeting this problem?

The only thing I can think is that the router in my office is built on the side of the house, ie the signal has to go through an outside wall, but nevertheless is this an insuperable problem?

Most grateful for any advice.

Could you do some think broadband speed tests for us please .. and link them in a post please?

What are the TP-Links?
A model number would help.

How are the TP-links connected to the BT Smart Hub?
Ethernet (the best), WifI (can be OK but often problematic) or HomePlug/Power line adaptors (terrible in my experience).

Any chance that your intervening wall has some cavity insulation that could be a screen? Try moving the router inside the main building to test.

If you really want any benefit from further wireless units, you should connect them with wired ethernet, because if they were themselves receiving good wifi, you would probably not need them.

In reply to a post by cjn:

Any chance that your intervening wall has some cavity insulation that could be a screen? Try moving the router inside the main building to test.

Or perhaps a building in which foil backed plasterboard has been used.

In reply to a post by longedge:

In reply to a post by cjn:

Any chance that your intervening wall has some cavity insulation that could be a screen? Try moving the router inside the main building to test.

Or perhaps a building in which foil backed plasterboard has been used.

Could drill a hole through wall if so and use a cable between .. usual rules about safe zones permitting..

The Tp-Links are WA850RE powered off the ring main. Are you saying I should cable them together off the Smart Hub which is next door? That's going to be difficult.

In reply to a post by FredaBasset100:

The Tp-Links are WA850RE powered off the ring main.

These things are really poor, they will be the cause of your issue. You need another solution.

No cavity wall insulation in that wall, but thank you for your response.