Here's a puzzle.
Last year I bought some hosting from a hosting company and pointed a number of domains that I own to run from this service. All domains working fine and publicly accessible.
Then a few months ago I was at home and realised that I could not view any of the sites. The browser would report an error. I assumed a temporary glitch. Back in the office, from my office machine and network, all the sites worked just fine. Back at home that same day, none of the sites worked. I tried multiple browsers on the same home machine, clearing the caches, restarting the machines, restarting the router, tried other machines on my home network, even tried an iPod - not a sausage. None of the sites would load. However, when I tried accessing them from my Blackberry I could see they were all working.
A few weeks ago, the sites started working again from home ... but then a day later had stopped! And that is the current situation. I cannot access the sites from home but they work from the office and indeed seem to work for any other user. One of the sites is for a local sports club - Godalming Badminton Club - try it yourself. If you have any problem let me know but I tried it just now from the office and it works and I am told by other users it has been working consistently over this period.
So it would appear that there is some problem with my local network or ISP. I use a cable connection from Virgin Media, connected to a Dlink DIR655 router/gateway/switch. I use OpenDNS instead of the default ISP DNS but that is one thing I have checked. I tried reverting to the default ISP DNS but it made no difference.
I used to think I was pretty savvy about this kind of this kind of thing but now I think I may have missed something obvious. Please could somebody suggest some steps to diagnose the source of this problem and/or tell me how to fix it!!