Router network odditity

Hi,
Not sure this is right group so forgive me if there's one more relevant.
I am running vista ultimate upgrade from earlier xp .
When on xp I connected to internet via router and had two pcs at one time
but removed one . Did the ultimate upgrade and had no problems. I recently
changes provider and received a new router which is dual standard cable +
wireless type.
Running fine since service started 24th January. Saturday Feb 2nd I lost
connection!
The router showed connected all fine!
Checked with provider and after three days!! got some advice which involved
disabling a network in the network sharing box. I find that whenever I
shutdown the pc identifies two connections and I need to disable and
re-enable to get on line!! It seems to be to do with the IPV4 and IPV6
connectivity .I know this is something relatively simple but can anyone
point to what setting should exist for regular connection etc? tia.
Stuart.