|Granted it's been a while since I had a dialup connection. Prior to taking my present position and movnig here 6+ years ago, I lived on 40 acres about 30 miles out of the city I worked in and used dialup. As you can imagine, I had a LAN going at the same time.|
I can't ever remember there being any issues having bother operating at the same time. I used private Class IP addressing for my LAN and my ISP provided my dialup connection with a public (ie: routable) IP address for internet communication.
This is why I answered as briefly as I did. Unless you're using the same subnet for your LAN as your ISP is using for your external connection, there can be no conflict.
Not only is it possible, but I used to both at the exact same time every single day that I lived on that acreage.
I doubt there is anything you need to change since you're most likely using a private subnet for your LAN. Just to be safe, lets check what TCP/IP settings you're using on your LAN:
Open a command prompt window (ie: Start >> Run >> type cmd and hit Enter) and perform the following command:
Once you've finished, copy/paste the output into a response on here so we can have a look.
For info on how to copy/paste from a command prompt window click on my name above and read my "how-to" guide titled, "Post the output of ipconfig (version 2)"
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.