I dont have another router but will probably have another cable. I'll give a cable a try and if the problem persists I'll try to get plusnet to send me a replacement..
Now I think of it, I have a cable running out of the modem round to my xbox one but it has never worked wired, I always need to default to wireless for it to work so perhaps it is the modem...
thank you all so much.
I will report back soon!