The phone problem does indeed explain it, but your 3.5Mbps connection speed masked the problem.
Your service is carried over a pair of wires from the exchange to you. If one wire becomes disconnected the phone will not work, but the broadband will at a very much reduced speed. Typically under 1Mbps.
If yours had been that low several people would have picked it up immediately.
Re that spacing, it isn't all done with spaces, just the final alignment. It is the bracketed directives round it that do most of the work. So if I hadn't adjusted anything, but just inserted the full stop - which as most things start with text I haven't done before - we would have had:-
. sync snr Mode
2011/03/24 12:56:04 GMT 1 7837 6.0 G.DMT2+ Annex A
to this @ 57.3db
sync snr Mode
2011/03/30 19:18:13 BST 1 3501 6.1 G.DMT2 Annex A