Bridge mode loses internet connection
So I've got my W9970 to act as a modem for an ASUS RT-AX58U for my TalkTalk broadband, when I put it in quickstart mode selecting talk talk UK it works when I connect my router in auto IP mode (as opposed to PPPOE) however that's a double NAT as the WAN IP is 192.168.x.x range.
When I add the bridge mode it continues to work however when I try to disconnect the original broadband quickstart option and the internet on the router disappears.
Is it a problem with the W9970 putting into bridge mode or is it the router settings? Talktalk doesn't have a username of password it autodetects you're on the right line. The settings are
Username
We use automated network authentication so there is no need for a username. You can leave this blank.
Password
We use automated network authentication so there is no need for a password. You can leave this blank.
Transfer Mode/Loop Encaps PTM
VLAN ID 101
MTU 1500
DNS Set as automatic (or similar)
Priority 0
Authentication DHCP/IPoE
https://community.talktalk.co.uk/t5/Articles/Set-up-a-non-TalkTalk-router/ta-p/2205383
Does anyone have an inkling of how to solve this problem?