Phone ringing kills DSL connection - but only in Master socket?

[HangTime]

Bit of a strange one this.
3x phone sockets, all with filters
Master socket just has the DSL router connected. Everything is fine until the phone rings, then the internet connection cuts out.

Now, the weird thing is if I connect the router to a different socket i.e. the one at the top of the house, this doesn't happen. This doesn't make much sense to me, as I would have thought it should be more stable plugged into the master socket rather than some dodgy daisy-chained one two floors above it?

Going to do some more extensive testing unplugging different sockets etc tomorrow and trying different filters, don't really want to annoy the neighbours right now. But has anyone had similar experiences on filtered lines?

 

[alex24]

Sounds like a dodgy filter to me, certainly had one or two go like that in the last 6-7 years.

 

[bledd]

This screams of 'broken filter' to me

Had the same problem in my mums house and many other friends houses

 

[Mattus]

Could be interference from the ring wire. It's useless and easy to remove.

 

[tolien]

If you want to try it at the master socket with no extensions, you don't need the filter if you just have the modem connected.