loss of connection Liverpool 9 area

[mick094m]

Have had this problem all this week each day service goes down late at night then re-appears early next morning then goes off again, then comes back at 4.00pm approximately every day since Monday.have rung up and been told that it is my modem,but how come if it a duff modem I am able to post this thread,any suggestions would be greatfull,when I do an ipconfig it comes up with a default gateway then when its off I cannot rew it via ipconfig/renew.
Anyone got any ideas,would it help if I installed arouter as I have got a likskeys Wireless G that I have not connected up yet,is it worth while doing so with this intermittent problem of connection
Thanks in Advance