Thank you for your help everyone!

All solved now - as it happens, moved apartment recently and the phone socket here gives no such problem! - we're not paying for internet here or last place (Korea's a bit funny like that) - so its a case of so far so good!

Incidentally, you kind folks were much more helpful than the system76 support guy I was in contact with, so consider yourselves professional!

Cheers all,

Gareth.