Getting through!

[#1]

Just having dinner. Do you mind starting again in the morning? I should be a bit fresher then. Thanks for all the sound advice up to now!

[#2]

No problem for me, @JoeR , but it will be after 10.00AM

[#3]

No problem I'll be back about 8 in the morning...

[#4]

Can I suggest that you also post a picture of the socket downstairs?
Are there any other phone sockets more than the 2 you mention?

[#5]

DSL in officeMain socket downstairs

[#6]

I think the problem is that the downstairs socket has not been wired to DSL.  The box in my office has two sets of cables - one for DSL and one for the phone line I suspect.  Could I easily cable the downstairs box from the junction box outside the house? Or do I need to get an engineer out?

[#7]

That looks like an extention socket taken from the filtered side of the main socket upstairs.
I'm not sure how to explain what to do, made harder by not knowing what the external wiring is like and where the phone line actually comes into the house.
Basically the BT phone line goes to your upstairs socket - its the master socket.
The downstairs socket is an extention or slave socket wired to the customer wiring part of the master socket .... after the filter built into the master socket. Result -- no internet downstairs.
Ideally you need a BT engineer to rewire and swap the sockets over so that the phone line enters the house via the downstairs socket.
In the short term (next 3 to 6 months?) I would suggest leaving things as they are and either using wifi from upstairs or put a tempory network/ethernet cable in for any "wired only" device.
I've just had to advise a friend of mine to do the same thing because I cant visit to sort out his internal phone wiring for the same reason.

[#8]

@JoeR  thanks for the photos. As @Bogbody  says , and I guessed earlier, you have a filtered faceplate fitted to the upstairs master socket.

Could I easily cable the downstairs box from the junction box outside the house? Or do I need to get an engineer out?

You cant cable the downstairs socket direct from the junction box, that would give rise to a bridge tap, which would likely reduce the speed obtainable. The only simple rewiring possibility would be to move the extension wiring, on the upstairs faceplate, from the filtered terminals to the unfiltered terminals. Whether this is even possible would depend on the type of faceplate you have.

TBH in the current situation I wouldn't advise this unless you really know what you are doing. 

BogBody's suggestion of an ethernet cable is a good one if physically possible. If not, then consider a pair of Homeplugs which enable networking over the mains wiring.

[#9]

Homeplugs or "powerline adapters" are an excelent alternative.
However without knowing details about your house mains wiring I cant be certain that they would work. I hesitate to recomend them before looking at house wiring and testing a pair.

[#10]

Bogbody - thanks for this.  I think you are correct.  I will wait for a few weeks until Covid is over(???).  In the meantime, what is a "powerline adaptor"

[#11]

@JoeR  Powerline is a method of using your existing mains wiring to transmit data. See here for an explantion https://www.techradar.com/uk/news/networking/powerline-networking-what-you-need-to-know-930691

It's an alternative to running ethernet cables. You plug an adapter into a mains socket at each point where you need a network connection and plug a short ethernet cable from your device into the adapter. In your case you'd plug in one next to the router upstairs and one downstairs where you want your computer.

As @Bogbody  says, the performance of these is dependent on the mains wiring. They do need to be plugged directly into a mains socket, not into an extension cable. You can get some with a pass-through mains socket to avoid having to take up an additional  socket. For examples https://www.argos.co.uk/browse/technology/laptops-and-pcs/networking/powerlines/c:30071/

Don't believe the quoted speeds though, they are the maximum under ideal conditions.

[#12]

@JoeR and @MisterW yes... powerline adapters are very useful. I use 3 myself.
However their successful use is rather dependent on the house wiring.
They dont work on extention leads. They are very iffy on circuits that are on a spur or across two ring main circuits (often up and downstairs or a kitchen vs the rest of the house.
Best operation is on the same ring main.
A look at the mains consumer unit can clarify the number of ring mains and their location. Spur wiring is usually out to an extention or conservatory.
This is why I dont blindly advise their use when an ethernet cable will work and be significantly cheaper 🙂
If you want to try some get them from a supplier that has no quibble returns.

[#13]

It’s great to think that there are experts out there who can help rank amateurs like myself. I think this is sorted so many thanks to you all for your help.