[Solved] Draytek Vigor 166. Frequently dropped connection.

Dobby_

I tried swapping back to the Openreach modem, which remained stable. Lastly, my ISP has arranged to send a replacement router (Fritzbox 7530) to test the line, but it can't be put into bridge mode so I'll end up with double NAT.

Cool, take it, you will be able to see the whole sync process
visually and on top you may be able to open the LAN port
to your pfSense as "exposed host", then you will be aware of double NAT!

Internet > DSL-Informationen
You may see there the problems better shown
Internet > Permit Access > Port Sharing
Set up "Exposed host", but only on the port for the pfSense

youngy

@stephenw10 Yes, the mtu of the interface changed. But, as you suggest, the dropped connections didn't.

youngy

@youngy Just to round off this thread, I contacted Draytek again and they supplied two alternative firmware for the Vigor 166. One of them (r15597_791_9cf83135b_beta) has been running for > 2 days without a dropped connection. Fingers crossed, that's given me a usable modem. Thanks for all your contributions.