Water ingress on external fibre junction box causing drop out?

[andymerrett2]

I got full fibre (FTTP) installed in early January this year, and after an initial reboot because it was connecting at 100Mbps, it's been great except for two disconnections (one of which I'm experiencing now).

The first happened on the first weekend in February, went down on Saturday evening and didn't come back up until Sunday evening (just under 24h later). The PON light constantly fast flickering during outage. An engineer came out on Monday by which time the broadband was back up and running and seemingly solid connection again. He couldn't do anything. From my reading around it seems like either some "handshaking" issue or "light loss" somewhere fairly localised.

The second has happened since mid-morning today. Same issues. I haven't logged it with BT as of yet.

The similarity is the wind and driving rain which occurred both times. I used to have a lot of problems with rain affecting the old FTTC and copper service, but outages only lasted for 5-10 minutes each time.

I know water and weather shouldn't affect fibre connections (especially one so new) but I am wondering if there has been water ingress into the external box which has caused some kind of issue where the two sides of the cabling join up. I don't know what's inside but there's a cable going in from the overhead cabling, and one coming out and going through the house wall to the ONT.

Having inspected the external box after this heavy rain, there whole thing is splashed and the top is wet. I also felt at the bottom just inside and the cables felt a little wet. There are two little oblong holes at the top which I presume let you open the front cover, plus one right by the wall. None of these seem to be externally sealed - are they sealed inside? Is it possible rain or runoff from the wall is getting into the box and causing an issue, and then I get my connection back when it dries out?

It could be something totally unrelated of course, but BT/Openreach can't see any fault externally and nothing has changed internally AFAIK.

Any thoughts? And could/should I try to protect the external box somehow? An extra cover/box over the top which I could then silicone? I don't want to restrict access or mess around with the actual box, as it is Openreach equipment.

[licquorice]

There is absolutely no way water ingress will affect fibre. The join between internal and external fibre is a fusion splice, i.e the bare ends of each fibre fused together to create a continuous fibre.

[andymerrett2]

Thanks. Must be something else then.

[iniltous]

As stated a spliced connection can’t be compared to a metallic joint between two copper wires , the fibre ends are  fused together and a  heat shrink splice protector  positioned over the splice , so no water ingress is possible, and once in this spliced and protected state would work perfectly happily completely submerged in water .

If there were an interruption to the ‘signal’ to the ONT , you would expect the LOS (red) light to be illuminated or flicker not the PON (green) light to flicker …it may be a coincidence that the problem is more noticeable during bad weather, as the symptoms seem more likely to be equipment (your ONT or the headend ) rather that the transmission medium (the fibre) 

[andymerrett2]

Thanks.

I've read a number of forum posts and elsewhere and seems sometimes there are issues which can't easily be tracked down. As this is the same situation as last time, I won't report it yet. I have the Hybrid backup which is acceptable to keep us going. It's only the second time so the weather link is likely tenuous (especially as it's rained plenty more that twice).

[andymerrett2]

Just for the record the fibre reconnected at around 3am this morning. Downtime ~15h. It was ~21h last time. Can’t determine anything from the logs. I have a horrible feeling this is going to be one of those intermittent issues. Thanks for your reassurance it’s nothing to do with water. ☺️

[iniltous]

Was the PON light ‘flickering’ during the outage or the LOS light lit ( some ONT models use the same LED but it turns Red for LOS (loss of signal) Green for PON .
If it was (as originally stated) the PON light , I doubt it’s the fibre as such and more likely to be the electronics at your end ( the ONT ) or at the OLT (headend) .
If your neighbour ( hopefully a very near neighbour  to ensure as far as possible they are on the same splitter/headend port ) is now connected and didn’t have the same issues as you , that would point at your ONT being the culprit as the OLT continued to work correctly for your neighbour ( and optically your services are identical to each other ) ….your router logs in this situation are somewhat irrelevant.

[andymerrett2]

Yes the PON was fast flickering throughout and the LOS never lit red (when observed of course). I suspect it’s the ONT. I suppose it could be a dodgy Smart Hub 2. I’d not used Ethernet port 4 which is now WAN before fibre upgrade. Anyway I’ll not push any more on this thread as the title is now misleading. If I build up any more evidence or data I’ll start a new thread if necessary. Ta. 

[36ULW]

Sounds like you’re getting an Intermittent Light Loss Signal.

Is the fibre fed overhead or from underground?

If it’s OH it might have a loose connection at the CBT Port and any wind/breeze is causing the Light to fluctuate.

Could also be the Fibre Bend Radius has been exceeded somewhere in the Network, come across that more often than not.

To be honest you’ll never really know until you get it reported and someone, hopefully someone who knows what they’re doing faults it.

I’d hazard a guess the problem is just localised to you though because PON’s are monitored constantly and if say the 22 ONT’s on said PON were to go down at the same time it would set an Alarm Off to be investigated by a PTO.

If it’s just one of 22 going off/on they’d assumed it was probably just that one Sub powering the ONT off and on again for whatever reason.

[andymerrett2]

It's overhead fed. Two significant (ie 12h+) outages in nearly two months isn't great but at present the chances of getting an engineer out who knows what to look at while the outage is still occurring seems slim.

First engineer arrived Monday morning when the connection had come back on Sunday night. If it's a physical issue then the issue will still be there, but perhaps harder to trace.