I just ran about 130' of Cat 5 ethernet cable from my house to my office in an underground conduit (that was a lot of work!). My setup:
- house has Comcast cable modem connected to original AirPort base station. This has worked great for over two years. But, I needed to get online in my office, about 100' from my house - airport signal wouldn't reach, even with external antenna, etc. Concrete block building/steel door must have interfered.
- dug the ditch, ran the wires, connected the Pismo, worked, but then house Macs didn't connect! Learned it was because I had an ethernet HUB instead of a ROUTER! Had to keep resetting the modem to change from house to office.
- bought a D-Link router yesterday, connected it, now, all is well in house using AirPort and in office using the ethernet cable...
I learned the difference between hubs/routers by STF (searching the forums) yesterday. I also ran coaxial cable, so now have cable TV in the office as well!
Just wanted to share this victory; maybe it will help someone else...