Since about April I have had issues with my adsl internet randomly dropping (wifi & ethernet). Currently I would say it happens 3-4 time a week for about a 10 minute period where I am lucky if I am even able to load a single page. Was especially noticeable and seemed consistent with the landline being used. I tried to replicate this but it worked fine when I tested it. At first I thought it was probably a line filter, I had a couple of spares so I swapped one with each phone in the house for a couple of days to see if it made a difference, nope. My modem/router was an old telecom thomson v8, I haved swapped that out with a spark hg659b as they are cheap to pick up, hasn't made a difference

Just now for the last 15 minutes and the second time today I have struggled to load a single page without getting constant dns errors / connection timed out messages etc etc, this is across multiple devices. Hasn't been raining much (as I started to wonder if that was related one wet weekend) and landline hasn't been used. House is about 15 years old.

I guess I should try a new line filter on the off chance both my spares are bad but, I also got a new desktop around the same time but can't imagine that being the reason for the outage the last 15 minutes considering the desktop is turned off, thoughts / any other ideas?

Edit: a couple of weeks back my house alarm went off completely randomly one morning (alarm was not even set & backup battery is ok)