Strangely intermittent Broadband

[#1]

I've been suffering major broadband problems for the last few days. Reported to Plusnet 2 days ago, but nothing forthcoming from them.
The internet works sometimes, but then suddenly you try a web address and it grinds to a halt. THe router doesn't report anything wrong, and sometimes other websites work fine simultaneously. Initially I thought it was only when using wifi, but subsequent investigations proved otherwise.
I've tried a different wifi hub but that makes no difference. I attempted to use a different router, but the old one I have as a backup does not seem to work with the iMac I tried it with.
Because the problems seem to be intermittent, it now seems more likely to be at Plusnet's side of the fence, whereas originally I thought it was router-related.
Any ideas anyone?

[#2]

It doesn't look pretty from what I can see.

Our tests aren't showing any particular issues but our Faults team will be in touch in the next 24 hours or so.

[#3]

Zantrop - welcome to the forum.
Are you able to account for the drops shown in the Radius Graph.
Can you post the stats from your router.
When there is a problem you are usually asked to try and run the connection with an ethernet cable to the router which in turn should be plugged via a filter
into the test socket (if there is one) inside the master socket.