WAN internet connection (PPPoE) inconsistant

I installed Openwrt on my Xiaomi router 3G last night and I was able to configure network interface to connect via PPPoE however there has been lot of random disconnection and connects back automatically.

But now its been 3 hours and still there is no connection.

I noticed that in/etc/config/network there is no entry for WAN however it is present when checked via GUI


config interface 'loopback'
        option ifname 'lo'
        option proto 'static'
        option ipaddr ''
        option netmask ''

config globals 'globals'
        option ula_prefix 'fdf9:37c3:39a3::/48'

config interface 'lan'
        option type 'bridge'
        option ifname 'eth0.1'
        option proto 'static'
        option ipaddr ''
        option netmask ''
        option ip6assign '60'
        option dns ''

config device 'lan_dev'
        option name 'eth0.1'
        option macaddr 'XXXXXXXXXXXX'

Here is GUI

Are you sure? Could you try changing anything in the WAN settings and see if it will show up in the config file, and if the changes will retain in the GUI after restart for example?

Could you confirm that the MTU is as required by your ISP?

What I am worried is the whole WAN part is missing in config file, I rebooted the router and checked both config and GUI just to confirm still missing.

There is no such requirement for MTU(have I added this somewhere?), ISP has only PPPoE.

Well, I guess you better delete the WAN interface from the GUI (if it's still showing there), and recreate it.

You can find the MTU for PPPoE under Advanced Settings tab of the interface configuration page

Apparently the issue was with ISP they had to bind my MAC inorder to get connection.

Weirdly if I uncheck "Use DNS servers advertised by peer" and use I don't get connectivity else DNS is provided by ISP

Also check that your MTU is correct according to your ISP. Usually it has to be 1492, but it can vary.

Maybe they are blocking third party Nameservers for censorship purposes.

This wouldn't be the case as I was using pihole as my DNS previously.

This is totally irrelevant from the PPPoE disconnects. You may accept or ignore the NameServers advertised by the ISP. In both cases you can add your own NS (in the second case it is kind of necessary). This works for the router itself and the hosts that use dnsmasq to resolve. If you advertise the pihole to your clients as NS, then they will query the pihole, but pihole also needs some upstream NS to ask.