In reply to a post by Axolotl:

The end result was the dropouts were caused by a faulty fibre splice from the original installation and a duff ONT. Openreach replaced both and it has been rock solid ever since.

A faulty splice, can cause intermittent issues along with a duff ont as you found out.

In reply to a post by Axolotl:

In my case, PlusNet blamed the router, my cabling and anything else they could to avoid admitting there was a problem.

Notably, whenever they tested, they could see nothing wrong, because when they tested, the connection was up and running.

Sadly when its intermittent issues, the above can happen, its frustrating for you because you are witness to it and the isp is not .

In reply to a post by RichG63:

Thanks everyone for the replies and ideas. I have now restarted both the ONT and Fritzbox and will monitor over the next week. If it still keeps dropping then I'll contact Zen to see if they can offer any insights.

Did you capture or save the full logs before you reset the router by any chance? Shame if you didn’t as that would have been very useful for fault diagnosis.

You will now need to wait for the faults to reoccur. Just something to be mindful of in future.

In reply to a post by PCJM40:

In reply to a post by Taras:

do monitor the ont as well, if you notice a drop in real time check that ont los light.

I usually setup a temporary indoor camera in these situations to capture the lights, its easy to then review the logs and lights at the same time.

That is a good idea,

Fritz!Box defaults to “clearing the internet connection” every night, dropping and reconnecting PPP.

To disable, open the UI and:

- Navigate to Internet > Account Information
- Expand “Change Connection Settings”
- Uncheck “Delay disconnection by provider to the period between”
- Click Apply

The connection should remain active 24x7. I typically have many months of uptime, usually only bouncing after a firmware update .

Edited by DougM (Sun 27-Sep-26 08:35:12)

....or change that setting to force this to happen daily at a time when it won't affect you (eg in the small hours of the morning). I have had mine (bought, not provided by Zen, and a different ISP for service) doing this since new ~5 years ago. Mine is set to between 1am and 2am. Never had any other disconnects to press.

The OP should be able to conclude from the logs if this is happening the same time each day, or if not then its something else…

There really should be no need these days to tear down a PPP session every 24 hours. The BNG can easily keep the session alive for months on end. Hopefully the router software is stable and suffers from no memory leaks for this to be required.

Edited by Pheasant (Sun 27-Sep-26 10:56:17)

In reply to a post by DougM:

Fritz!Box defaults to “clearing the internet connection” every night, dropping and reconnecting PPP.

To disable, open the UI and:

- Navigate to Internet > Account Information
- Expand “Change Connection Settings”
- Uncheck “Delay disconnection by provider to the period between”
- Click Apply

The connection should remain active 24x7. I typically have many months of uptime, usually only bouncing after a firmware update .

For what reason? Seems a strange thing to do, I have never known that from any router i have had or seen.

I checked and my Fritzbox didn't default to that mode of operation so not that.

I have never known that from any router i have had or seen.

My Fritz!Box 3940 (3490? dunno some collection of those numbers ) used to do it for FTTC... i don't think it does now its an AP for the ISP supplied FTTP router.

In reply to a post by RichG63:

I checked and my Fritzbox didn't default to that mode of operation so not that.

Have you logged the fault with Zen support?

What are the router logs showing - stable or any more (random) session disconnects?