It would depend on what kind of DVR you have.
Yes the shop would have to have high speed internet connection.
You would only need a router if you have multiple devices to connect to the internet. The router would make it easier for you to set it up.
You would also have to have high speed internet where the remote computer is going to be viewing the DVR.
Note:
You may have to make changes on computers. You will need to go to internet options > security tab > custom level > active x
You will need to select prompt for download unsigned active x controls.
Some DVR may have a disc that has software. They may have a "find dvr" selection.
High end DVRs such as Speco will help you with the router setup based on certain brands, and models of routers.
http://scorpiontheater.com/videonetw...ithavtech.aspx