Vista - connection problem after reboot

This problem is for Vista only.
Some people have problem on Internet connection after reboot, and so do I,
but I have tried many solutions suggested in these posts.
The general situation of this problem is like this:
After boot, reboot, sleep, or any kind of restart, you found yourself need
to do the diagnose & repair to get connection back.
There are a few suggested soluions:
1. disable the IPv6 from the property page of the NIC
2. check to see if your NIC driver is selected to power down for power
saving in the driver page
3. add another NIC to your computer
and I have found the solution for my computer:
4. disable the "routing and remote access " service
I found it out as i discover i have a brief moment of connection to web
pages and then lost it after all service loaded, so i tried to disable them
one by one, reboot,try to go online, repeat again. and figure out this
service is responsible for my problem. Now i would like some explain of what
this service does exactly, and how it cause the problem? Why it does not
cause problem for my XP on same computer but Vista only?