I have a Draytek Vigor 2710Vn.

I have both a DECT phone and a corded/wired BT Decor 310 phone connected (via a splitter) to the second voip phone port (which is setup to use BT Broadband Talk).

When someone rings the PSTN number and I pick up using the wired phone the Vigor 2710Vn immediately hangs up.

The DECT phones work fine.

I have tried removing the splitter and only using the wired phone on the VOIP port but the issue still occurs.

The wired phone works fine when plugged directly into the wall socket.

Any ideas?