The PlusNet member centre page gives exactly the same "current line speed" as it did before (33.8 Mbps). That's about what I get from the BT Wholesale speed test but, as before, it won't give me an IP profile. When I try the Further Diagnostics option, it still says: "Your speed test has completed and the results are shown above, however during the test an error occurred while trying to retrieve additional details regarding your service. As a result we are unable to determine if the speed you received during the test is acceptable for your service. Please re-run the test if you require this additional information."

In reply to a post by greenwich:

The PlusNet member centre page gives exactly the same "current line speed" as it did before (33.8 Mbps).

I suggest you give them a nudge to get it updated. The engineer has confirmed you are connecting at full speed so, irrespective of the fact you can't get an IP profile, it should be set to the highest possible value.

Their text to confirm the engineer's appointment said they could take up to 72 hours after visit to get back to me. I will give them time and then call them, though I gather there are longer waiting times right now.

Some good news at last. Plusnet texted me to ask me to reboot the router. Doh! An obvious step but I hadn't thought of it and nor had the BT engineer on Saturday. Anyway, after rebooting, my speed via the ethernet cable has shot up close to the 70 Mbps level:

http://www.thinkbroadband.com/speedtest/results.html...

The bad news is that the wifi speeds have gone haywire. I tested the speed by wireless in the bedroom where last Saturday I tried and failed to stream Match of the Day because the speed was too low. I got about 2 Mbps at first. Then less than ten minutes later, the speed was up to 35 Mbps. I got a 5 Mbps reading in the other bedroom, where I used to get up to 20 Mbps before.

Will have to keep an eye on the wireless speeds and hope they settle down to a good value, as we only use wireless, since the router is in the hallway. In the meantime, thanks to everyone, including Plusnet, for the support.

If there are several wireless networks in the area the only option will be to upgrade and add a 5GHz wireless access point.

... and hope the rest of the kit supports 5GHz.

Wireless speeds still poor upstairs. Plusnet have said that my wireless issues are not regarded as a fault. They have referred me to the advice on their website about how to improve the wireless signal and I will try it at the weekend. I was also thinking of MrSaffron's suggestion of buying extra kit, though that will need some research.