The yellow ones don't need to be disturbed. The red ones are cheap and should be replaced.

But best don't disturb any of it unless you really really have to. Leaks behind there are very hard to detect, until the furniture/floor chipboard goes all soggy and swollen. (Shudders at this memory!)

The grey 90 is easy and cheap to replace, but you’ll be disturbing the seal in the T on the main stack, i’ve never seen a seal alone be replaced , the whole fitting is. But if the T needed replacing it turns into a bit of a mission. Is the new data cable really that important?

If you were to need to change the toilet , you’d only be disturbing the two red seals in your picture. But yes if the yellow was disturbed first off it’d just be greased and replaced, unless it’s damaged , gone hard or displaced.
Assuming you solve the w7 wifi issue then a wireless access point (WAP) on the ceiling over the stair well is a straight forward solution in many cases, or if you’ve got a power socket in the loft use a power line ethernet device then you can hardwire your desktop at other end. I used a tp link device in my last house.Worked fine.

I don't like the idea of a socket in the loft being in permanent use (OK for occasional inspection lamps etc) I would prefer any powered equipment to be hard wired or connected with something like a wago connector that has certification for use in non-accessible places (but there are restrictions about how they are used)

Posted By: RexIt was all passed by the BCO when he inspected.

He doesn't pay for the fire insurance! I'd be more concerned about how the socket is connected and fused. Not part of a ring or an unfused spur I hope. And with a networked fire alarm up there.

Are the coax cables in situ?

Power line adapters send internet over power lines, but you can get similar things that send internet round the house over any unpowered cable, eg old phone cables or coax TV cables. Search 'MoCA adapters '

Is there something about sockets in loft spaces being especially problematic? Surely if installed and used correctly they represent no more of a risk than any other socket in a home. For the intended use of a powerline adapter and to power a router the amount of current is going to be negligible. Akin to having a tv plugged in , does anyone worry about that? ( not to mention , pc, printers, hifi, coffee machines , washing machine, boiler, mvhr).

Posted By: ArtiglioIs there something about sockets in loft spaces being especially problematic?

No more problematic than having a plug and socket anywhere else that is out of sight, never visited, and only attended when a problem arises - by which time it might be too late.

The regs allow a socket in lofts but they must be on a spur (not a spur off a spur) and have RCD protection (the house RCD will cover this)

IMO permanently used plugs and sockets are a bad idea in places that are not in plain sight.

Pih - all but my first home , i’ve had sockets in the lofts , but they’ve either been part of the ring or spurs. All protected at consumer. In my flats they run from the landlords supply so added benefit of no chance of tampering by tenants.
As part of a council landlord event , we had a talk from fire service. We were told the instances of fire from the fixed installation were rare and even more so in imstallations that had eicr’s ( electrical installation condition reports).
Fire service reported more fires from faulty consumer electrics, the most common are the use of cheap chines chrgers and extension blocks, being used in bed and tucked under pillows. With fires related to scooters and ebikes being the most rapidly increasing problem.
My electrician , when looking for trip faults. Usually associated with kettles, toasters and coffee machines in kitchens or irons. Either dodgy power cords (irons most common) or the sockets arcing out over time when used with high current items kettles, toasters etc.
Issues i find , the sockets where hoovers plugged in cracking as people try to reach further than cord wants. Non uk 2 pin chargers used in sockets with a cocktail stick , bit of wood, plastic etc used to bypass the earth safety to enable the 2 pin plug to be inserted.

There’s a bit of push back on using fixed fued outlets in last year or so. These days electricians prefer to connect the likes of boilers , aircon etc using plugs into sockets. It’s considered far safer. People were just turning items off and not removing fuses to isolate appliances and this has been deemed too risky. By using a plugs into sockets and socket, it’s much easier to fully isolate by removing the plug from the socket. My last two boiler instals are installed this way along with an mvhr.
Of course it’s equally easy to reconnect. One electrician i use also likes it as it reduces the risk of damade to the fuse carrier on an fcu where people have levered it open with whatever first cones to hand. If he comes across one he chanes it to a plugs into sockets and socket unless customer objects.
But not done for higher current devices that switch on/off repeatedly ( hobs, ovens, etc) as they can arc within the plug/socket over time.