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ONT issues with Zen Business fibre 900

tyrex

Casual Member
Been having issues with our Zen internet connection dropping approximately once a month and not coming back up by itself. We do see the occasional drop and automatic reconnection by our Fritzbox router in its logs, but these particular drops are different because the only way to resolve is to power the BT OpenReach ONT off and on again.

This is what the ONT & Router look like when the connection is down - three green lights on the ONT (no flashing on the LAN indicator compared to when the connection is working), and a red warning Info light on the router:

Zen tech support have been totally useless, they keep asking us to change cables etc. to no avail. It seems impossible to get them to escalate to OR and we keep getting fobbed off with 'just sounds unlucky' excuses.

It's happened four times in four months so far and is a real pain because some of our staff VPN into our office over the weekend so we are forced to visit the site in order to reset the ONT.

Has anybody seen this before?
 
your vid is private btw
 
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Whats the label next to the red light? its unclear sorry.

ONT, FTTP link to exchange looks like isnt the problem though, unless its somehow in a state it's reporting everything ok on the LED's but has stopped passing traffic.

I can completely speculate, but its speculation.

Zen are known to disconnect PPP sessions during the night, it could be the router for whatever reason isnt behaving well with it, and rebooting the ONT which will actually temporarily disconnect the ethernet might then trigger PPP reconnecting.

To test my theory when it next happens you could unplug the ethernet wait a few seconds then plug it it back in and see if it recovers it. Likewise you could reboot the router instead of the ONT. If neither of these works and only rebooting the ONT brings it back up, then it might be worth asking for an ONT swap or something.

Generally speaking when there is an outage, it is a good idea to determine if its the access network (in this case FTTP) or the ISP session (in this case PPP). You should be able to see the PPP status in the GUI for the router. Although I am guessing that red led is indicating the WAN/PPP is down.
 
I suspect causing a layer 1 disruption (link loss) on a routers WAN port is in most software going to be a call to action that any stateful protocols dependant on that interface have to restart themselves, PPPoE included.

But causing a loss of connectivity at layer 2 without disrupting layer 1 - for example by putting a managed switch between the ONT and router and deconfiguring the active VLAN and later reconfiguring it would likely be a better and more realistic test (an unmanaged switch could also do the job, disconnect the port to the ONT but leave the port to the router connected)

It's a bit more involved, but YMMV
 
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The Fritzbox logs should show the PPPoE session dropping, it's either Zen's gateway giving up, or it's the router they supplied having a problem. In any case, it's Zen's problem to solve and Openreach visits will not achieve anything.

The suggestion to put a switch in between the ONT and the router is a good one, I would be surprised if it's a physical link issue as the ONT has a nice green LAN light on it.

All I would add is that I saw this the other day (point 8) and there have been some noises made about the ethernet ports being hit and miss sometimes. Try disabling EEE.
 
Interesting insight, thank you everybody for your thoughts.

Had a look at the Fritzbox logs but it looks like the logs expire after a few days so I can't see what happened to the PPP connection at the time of the last dropout. Will have to see what it says next time it happens.

We did try restarting just the Fritzbox before but that didn't achieve anything, only restarting the ONT got things going. However, I think I will give it another go when it next happens, as we've only restarted the Fritzbox first on one out of the four times it has happened (once bitten, twice shy etc. etc.)

Will also take a look at power management & getting a switch in the middle, we have lots of spare kit.

Thanks again :-)
 
Another update. The connection dropped again at the weekend, and fortunately I could be on site to diagnose. Long story short, restarting the Fritzbox makes no difference, nor does disconnecting/reconnecting the ethernet cable between the Fritzbox and the ONT. Restarted the ONT and 2 mins later everything sprang back to life.

Called Zen support and they agreed the fault was higher in the network so sent OpenReach to us today who - reluctantly - swapped out the ONT. It's a different model too. The engineer said they weren't usually allowed to swap ONTs and didn't think it would help anyway. He believed the fault lied within Zen's network somewhere upstream from the ONT.

There's a loose pattern to these drops by the way, it's about every 29/30 days and fairly consistent, i.e. never earlier or later. Not sure if that's indicative or not?

Anyway, I'll give it another month or so and see if the swap helps.
 
Another update. The connection dropped again at the weekend, and fortunately I could be on site to diagnose. Long story short, restarting the Fritzbox makes no difference, nor does disconnecting/reconnecting the ethernet cable between the Fritzbox and the ONT. Restarted the ONT and 2 mins later everything sprang back to life.

Called Zen support and they agreed the fault was higher in the network so sent OpenReach to us today who - reluctantly - swapped out the ONT. It's a different model too. The engineer said they weren't usually allowed to swap ONTs and didn't think it would help anyway. He believed the fault lied within Zen's network somewhere upstream from the ONT.

There's a loose pattern to these drops by the way, it's about every 29/30 days and fairly consistent, i.e. never earlier or later. Not sure if that's indicative or not?

Anyway, I'll give it another month or so and see if the swap helps.
I think Openreach are full of it.

The ONT doesn't have the session for Zen on it, so if the ONT needs a power cycle to restore service and you've restarted the router (as you have said) each time then the ONT is faulty in some way and it is the ONT to blame. Zen should have been able to figure that out pretty easily if they'd listened to what you told them you'd been doing - once you've tried restarting the router and the problem doesn't clear, and the only way to clear it is the ONT needs power cycling, it has to be the ONT.
 
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