Netgear N300 bridge mode question

Hello, I have a question about setting up an N300 router.  As a mechanical person I'm not to computer savy so I'll try and not irritate you smart people.  In my house I have ATT&T DSL, that's all that's available in my area. I'm running one computer off of it, nothing wireless in the house.  I have hard wired 125 feet of cat5 wire from the ATT modem to my metal shop that's 30 feet from the house, that is plugged into the new Netgear N300 router. My shop is only 30 x 30 so the signal doesn't have to go far to reach my laptop, cell phone, or whatever.  I was told by the person that sold me the router that it needed to be set up in "bridge mode".  I went through all of the set up wizard and never saw an option to do this. However, it seems to work pretty good, a little slow.  My question is should I leave it alone or try to configure in bridge mode?  I saw somewhere on the internet that bridge mode exist for this router.  Thanks..