In reply to a post by RichG63:

Are there any logs from the Openreach ONT that I can see, like is it losing sync?

Nope! All ONTs from Openreach is locked down!

i may have read that log from top to bottom, not bottom to top...........

😅

The next step is a support ticket with Zen with those log records. They can check with Openreach whether your ONT is dropping or if they're seeing your router terminating the PPP session.

As the log is only to the nearest second, and I am unsure whether the FritzBox guarantees the logs are in the correct order within a given second, there are two possible interpretations.

One possibility is that the IPv6 prefix delegation expired, causing the FritzBox to tear down the PPP session.

The second possibility is that Zen has torn down the PPP session.

Given that this drop happened at almost exactly 0500, when Zen sometimes tears down sessions for load balancing or maintenance, Zen may have torn down the session. However, 13 drops in 9 days is abnormal, and I would contact Zen support.

I am on Zen via Openreach FTTP, but my router is a pfSense virtual machine running on a Proxmox box, so I don't have experience with the Fritz routers Zen supplies. I can say that Zen's IPv6 is rock solid on pfSense.

OP has only emailed a snippet of the entire log, would be in their interest to check the timings of the other disconnections. Something is dropping the session, the IPv6 delegation being lost is just a side effect.

It’s either Zen forcing a reconnection from their end - which would strongly correlate to this occurring each day around 5am. Or it’s more random which would indicate a fault of some sort, possibly the router itself or a random network fault.

I agree with everything you say. While the posted log snippet is consistent with a planned session drop by Zen, I cannot believe that all the drops fall into this category.

As been said, have a word with Zen, have you tried resetting the router or just restarting it?

I had a problem months ago where things we not working too well and I restarted my router and things were fine. How long have you been on the service?

My fibre only drops when my network provider do a softweare update and that is early in the mornings.

As also been said, nothing to do with IPv6.

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.

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

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.