Three broadband roter

I have been using a ID sim in a Three broadband router for some months and it has worked fine. Yesterday it stopped working and the network red light was on. I tried the sim in my phone and it worked fine and the iD sim from the phone gave the same red light on the router. I have obtained another router and I am getting the same result- red light no internet. I don’t use a lot of data and I am at a loss as to what has happened? I understand that ID don’t actually do data/ broadband but I don’t see why it would stop working and as I said it’s worked great for months. Can anyone help before I have to find an alternative.Thanks.