Solved New ISP - WAN Setup - Will not work with custom WAN DNS - dnsmasq.conf

[stilltravelling]

I just moved over to a new ISP (brsk in UK - 900 down 900 up) today and have some weirdness going on.

I am able to connect WAN through Automatic IP when Connect to DNS Server automatically is set to Yes and devices successfully connect to the Internet.
If I choose No for Connect to DNS Server automatically and then populate the DNS Server1 with 1.1.1.1 for Cloudflare, the connection seems to succeed but I am unable to connect devices to the Internet.
The IP is actually static, but even when using the IP address, the Subnet Mask to 255.255.252.0 and the gateway (matching what automatic IP had picked up). Again I am unable to connect other devices to the Internet.

Somehow I've managed to discover a workaround. I've set resolve.conf to..

nameserver 1.1.1.1
nameserver 1.0.0.1

And resolv.dnsmasq to ...

server=1.1.1.1
server=1.0.0.1

Then run

service restart_dnsmasq

Testing in dnsleaktest.com comes back as all cloudflare, so this is great. Exactly what I want but looking to automate these steps if the router reboots etc.

Just to note. I can change the LAN DHCP Server DNS settings to 1.1.1.1. However doing this then seems to stop local access to my test web server. I think this happens because it queries Cloudflare first this way.

Is there anyway to run a script once the connection to WAN has completed and then I can overwrite /tmp/resolv.dnsmasq and /tmp/resolve.conf and then restart dnsmasq

Feel free to laugh, I'm using ASUSWRT-Merlin RT-AC66U 380.70-0 Sun Apr 8 18:04:34 UTC 2018. Still going very strong after so many years.

I'm trying to hold off buying a new router. If I do, I'll probably looking at some mesh solution, but these are mega expensive from what I've seen.

 

[stilltravelling]

I managed to solve this in the end.
Under Special Requirement from ISP I had to add customers.brsk.co.uk under Host Name