Ok guys, put your Sherlock hats on for this one, I've got a mystery to solve.

Here's the situation, a club has a DSL (through Orcon) at thier clubrooms on an airfield. This is connected oddly enough to a computer. People have complained that they often cannot get on the internet. Whenever I am there it magically works. I'd always put it down to just flakey DSL (I use cable myself). The system runs a weather station and uploads data to the net, I don't check that much but others have said sometimes the data is old.

On Wednesday night after more complaints I decided to go add some more ram, and a web cam I had, Once again, system was working perfectly, I added the ram, and pointed the cam out the window.

Thursday morning I took a look at the cam and the weather at 9:30am, all working sweet. I looked again at 12pm, and to my surprise the last cam and weather update was at just after 10am. At 6:20pm it still wasn't updating, so I figured somebody must have switched off the PC or it crashed or something.

So I drove out there and arrived at just after 7pm. Of course, the computer was running fine, and had just updated the web files! I checked the webcam software and it had snapped pictures all day, so the system wasn't crashed or off, the FTP log of the weather stuff showed it attempting to update but not connecting. The system must have dropped it's DSL between 10am and 7pm.

Today, everything fine until 9:30am, now it's gone again.

So,what could cause an otherwise correctly setup system, which is on 24/7, to lose it's DSL for a number of hours a day? The only thing I can think of is some sort of interference on the line from electrical equipment or something that is getting turned on in the morning and off at night, but unless that equipment is directly connected to the line, I can't imagine it's very likely, and what equipment that is connected to the line would do that and only be switched on during the day?