Losing connection several times a day

[#1]

I seem to have the issue described in this service post;
http://usertools.plus.net/status/archive/1422641789.htm
I am regularly unable to make new connections (websites, games, etc.), but I will still have a connection to things that are already open. For example, I can still view Twitch streams as long as I don't refresh the page, I can still connect to people in street fighter 4 as long as I don't restart the game. Rebooting the router seems to fix it but not sure what else I can do.

[#2]

I don't think the problems you are experiencing are related to that problem. That basically means that you wouldn't be able to connect to the internet at all (and it's since been resolved).
The information that you've provided would suggest to me some sort of internal issue. As rebooting your router resolves the problem, can I asked if you've been able to test with another?

[#3]

Could it be a dns issue.
Some people have fixed a similar sounding problem by configuring google dns or opendns in the PC network settings.

[#4]

I have switched between Plusnet & google DNS frequently, the problem remains.
I don't have any other router to test this on.
So far I just log into the router via telnet and do;
ppp ifdetach intf=Internet
ppp ifattach intf=Internet
to reconnect. Usually works the first time but sometimes takes several reconnection attempts before I get Internet.

[#5]

Does the routers log show a reason for this?

[#6]

Happened again at 10:40, logged into Telnet a couple times before I could get my connection back again.

[#7]

That log just shows you dropping the ppp session.
Did you try configuring opendns directly in the PC's network settings or just change the dns in the router?
You could try the following two ping tests when you next have this problem.
ping bbc.co.uk
ping 8.8.8.8
If the first fails with time outs and the second gives no errors then it's most likely a dns issue.