Right, they've come back with;

This is an unusual case.

If it was a problem at our end then i suspect that the site would not work at all, that it does show for 2/3 mins after a reboot suggests that the problem is more likely to be at your end unfortuantely.

Since you have a router there will be a built in firewall included with it, you may wish to check that or any logs it may have.

Also can you provide us with a tracert to the site when it is working?

Finally we can rule out your account as an issue with a dial test, this basically involves connecting as yourself so we'd need you to be offline at the time.

If you want us to do this then please specify a decent time window for us to test within, we have a night shift if this is more convenient for yourself.

I'll get them to do a dial test tomorrow.

They've asked me to provide a tracert when it's working. How do I get this as it dissapears when it connects?

Also, how do I check it's not my router?

Thanks again peeps