I've had this Infinity circuit for several months now and it has worked stably with an OpenReach VDSL modem and a netgear firewall. I replaced the netgear firewall with a 2925n+ yesterday - the OpenReach modem is still in place. The Infinity WAN connection (WAN1) was set up using the wizard, and is therefore set to "always on". There is no WAN 2 at present.

All looked fine yesterday night but when I came back to the 2925n+ admin console this morning, it was showing the WAN circuit disconnected, and devices on the network were not able to browse etc.

I can't see any reason why it would drop the circuit if it fell inactive, but that's how it seems to be behaving. I started doing things on my PC which caused internet (WAN) access attempts and seemingly without my doing anything to the 2925, the WAN1 circuit connected.

Any ideas why this is happening, and what to do to make it stay up all the time?

PS I installed the latest firmware from the Draytek site - 3.7.4.2 - while I was preparing the 2925n+, so the above behaviour was observed while running the latest firmware.

Try changing the WAN port speeds under WAN - General Setup - WAN1 to see if that helps. Otherwise check the telnet interface "log -ct" would show whether it's attempting to bring up the PPP interface and why that's failing.
Also change the WAN connection detection to ARP Detect if you've got it set to Ping Detect, to see if that helps.

Thanks.

Already set to keep alive based on ARP, so no way forward there.

Re

Voodle wrote: Try changing the WAN port speeds under WAN - General Setup - WAN1 to see if that helps.

The "Line Speed" (Downlink and Uplink) settings are grayed out because there is only one WAN connection, and I think those speed settings are only available when speed-based load balancing is in effect.

Are you referring to the "Physical Type" setting? (which is currently set to "Auto Negotiate", but offers alternatives of 10/100/1000M and full/half duplex)

try the alternative of the auto-navigation for 1000M & also make sure you have the correct MTU (i think is 1492) and see if still fails