I thought this might amuse some of you – it made me laugh!
My Verizon DSL connection gets sick sometimes, particularly during and after heavy rain … well it rained last night, and this afternoon the connection is dropping out every few minutes; the modem reverts between steady DSL light, slow flash, fast flash, steady (for a few minutes) then back to flashing, etc.
I thought I’d call Verizon DSL help; silly me!
First, I had to lie about having rebooted my computer, not having a router, etc, etc – all designed to get rid of me quickly and with minimum effort. Only after that was I able to reach a person (in India, apparently).
Next, the lady decided that I should remove the DSL filter and have the DSL modem be the only thing connected – I explained that (a) this would disconnect my phone call with her and (b) it wouldn’t prove anything since the DSL modem fails intermittently anyway. But she was not to be dissuaded, so I did it.
I also pulled out a trump card – I had a different DSL filter (Verizon supply many and I need only one) … so after disconnecting the filter, and confirming the DSL modem was unaffected, I replaced the filter with a brand new one!
She called back (my phone re-connected), and I told her that the brand new DSL filter was fitted but still I lost DSL connectivity – it dropped again right on cue!
But she had a trump card of her own … swap the two ends of the wire between phone connection and DSL modem! What?! She was convinced that this would resolve my issue; there must be “one way” signs inside the wire 😉
So I swapped the plugs over and of course for a while the DSL connection didn’t drop – she concluded her work was done …
Currently, I seem to have “happy electrons”, now my wire is the right way round; can’t understand why there isn’t any “modem this end” labels on the cable if it’s that important 😀
[and look, she must be right, because I was able to post this without the DSL dropping!]
M&I / GBMINI 
Of course, right after I posted this, DSL was down for the rest of the night! OK today, with dryer weather …
Expensive monster cable also has directional markers on their connectors. I always got a laugh out of that. Why not also place the modem lower so gravity can help siphon the signal in? Hah.
Your not alone Ian, my Verizon DSL has the exact same symptoms. They even sent me a replacement modem which did nothing to help my issue.
I had a similar behavior at my mother in law’s house where everytime it would rain it would drop out. I had troubleshooted it several times but moisture was the one constant.
Just before calling AT&T, I decided to replace the entire run of CAT 5e from the D-mark over to the computer and got rid of all of the indiviual filters at each phone and went with a single filter at the dmark to split the DSL from the pots. Happy to report that all has been well since.
Randy, sadly I’ve done all that – I have a 2 way in the Verizon wall fitting, with the filter in one side to the house wiring, and the DSL modem in the other side.
And the wiring from DSL modem to computer is a 6ft cable.
I wish I could fix it like you did 😉
Ah yes, welome to the highly technical world of Verizon DSL. I’ve been fortunate with not much dropping of connection, but have had weekends where calling support was much like puling my own hair out. Never heard of wires being directional, but this must be a new thing and will be suitably noted in my knowledge of electronics! I would love to have Verizon FIOS, but Kingston appears to be on the list for 2020 or so. My buddy in the UK has had it for over 15 years now, in Romford. Copper wire? Best of luck Ian, you’ll need it with their support people! Wait until they tell you that Apple and PC’s are not compatible with a Linksys router! They really attempted to push this as the problem I had last year. Duh.