Hello!

I am trying to solve a crazy mind bending fault!  It took me a lot of investigation to arrive at identifying the point of issue/failure.  I won't describe our home network in detail now but I can say it is pretty basic with a few normal settings customisations.

The issue is this: since my partner got a new notebook (Lenovo X1C with USB dock), which is connected via the dock's ethernet NIC, when that PC goes into sleep mode manually or automatically, if no other PC's are active on the ethernet LAN, then the Fritzbox 7530 drops it's PPPoE connection.  The VDSL is absolutely fine and never flinches.  It is 100% reproducible. The event log has 3 messages when the link goes down:

IPv6 internet connection was cleared; prefix no longer valid.
Internet connection cleared.
Timeout during PPP negotiation.

Then PPPoE Error: Timeout messages continue to be logged until, when that PC is brought out of sleep, the PPPoE is reestablished after a few minutes with event log:

Internet connection established successfully. IP address: xxx.xxx.xxx.xxx, DNS server: 111.69.69.68 and 111.69.69.69, gateway: 111.69.7.41, broadband PoP: SNAP-41

Some other notes:

- the connection won't be dropped if other PC's are awake on the LAN, but will if only WLAN devices are active
- we have a static IP address
- internal ip range is 10.1.1.x with some static IP's below .100 and DHCP above that (has been this way for 11 years)
- recently disabled IPv6 for internal network at Frtizbox (no change)
- recently replaced 7390 with 7530 (v7.28) and that has had a couple of resets (no change)
- all PC NIC settings are at defaults (and have been reset)
- ethernet cables have been swapped out and tested

Just to re-iterate, the (centrally filtered) VDSL connection is very stable and shows no errors.  We've had a flawless network and VDSL setup for 11 years until this notebook came into the house!

I've got no idea what to look at next.  Any thoughts would be hugely appreciated!!

Thanks