Inconsistent connection speed

[#1]

Good evening

For the last month or so, our connection has been extremely poor and frustrating. The following are examples of some of the issues we are experiencing:

BBC IPlayer buffers constantly and refuses to play files.
YouTube will constantly buffer, even attempting to play videos on 144p. A 5 minute video will usually take around double the time to play.
My smart TV refuses to connect to the WiFi network at all now. The network is visible but the TV just times out attempting to connect.

When running speed test programs, results can now vary from 29mbs to 0.2mbs. I used to consistently achieve 59mbs on the same network, router and WiFi frequency.

My phone now has a live data transfer counter. When I attempt to download an app or a podcast, you can see that the connection spikes up at 5mbs, plunges to less than 1kbps, then climbs to maybe 2mbps, then plunges again. The speed does not stay consistent at maximum speed, instead it 'spikes' all over the place. As there is no consistent data transfer to our devices, buffering is occurring.

I'd appreciate if this could be investigated

Many thanks

Adam

[#2]

Sorry to hear you're having issues with your connection.

We've tested your line and that's not showing any issues.

Are you able to connect any devices over a wired connection to see if you have the same issue?

[#3]

I have now sourced a cable and will try this evening when I am at home

As an update, the following sites also do not work/buffer significantly whilst attempting to access them through WiFi:

BBC News - Videos in-app buffer constantly, and even picture content in news stories appears pixilated, taking several seconds to load to a viewable resolution.

Twitter - Videos in app buffer constantly

Various commerce websites - My wife attempted to make a purchase from a website this morning, however she had to switch to 4g as the WiFi kept timing out, releasing the contents of her shopping basket back.

However, the following sites DO WORK over WiFI connection, without any router reset or channel switching etc:

Netflix - Works fine through both phone and set-top box

BT Sport app - This was able to work perfectly, and display the Man Utd vs PSG match on Tuesday evening in perfect HD, The WiFi was also able to support Chromecasting to my Nvidia SHIELD in HD without buffering or stutter.

As such, i'm confused why certain applications are perfectly usable, but most internet is essentially not working at this time? 

I will test the same applications through wired connection tonight and report back