Openwrt router and strange Internet behaviour

[r4w]

Hi! I have been using OpenWrt as my main router for over 6 years now and moved providers before without any particular issues in adjusting the wan configuration. This morning, I moved from Sky to BT and I applied the usual pppoe configuration:

U:bthomehub@btbroadband.com

P:BT

The router is able to get both ipv4 and ipv6 addresses over pppoe but only selected websites seems to work.

For instance, I am unable to reach https://checkip.amazonaws.com/ to check my public IP but I can use Google, reddit or nest.

I initially suspected a DNS issue but I can definitely resolve all those addresses, tested via nslookup or dig. 

I tried to change the username to my BT ID but I do get a very strange internal IP that it just does not work. 

However, the Hub seems to connect and work, but if I do a test connection it returns:

"You have a stale or inactive Point-to-Point Protocol (PPP) session." 

I restarted the hub a few times as suggested but the test always fails and it wants me to book an engineer. But my connection works, so I am sure what an engineer can do onsite for a problem like that. 

I am at loss on what the issue could be, currently using the Hub as "modem" and OpenWrt as access point to avoid reconfigure my whole network.

Did anyone experience an issue like this one before? Any help is greatly appreciated! 

Thank you 

[Crimliar]

Double check your NTP settings on the router.  If the router is acting as an NTP server and intercepting NTP calls then try disabling the router NTP.

With AsusWrt what you are describing can happen when you fiddle with the DNS settings a little too much, but often only hits after the clocks change (it shouldn't I know, UTC and all that, but it can happen).  Hence the try fiddling with the NTP.

If you can't get it working, I'd restore a previous settings file, or reset the router and keep as many of the settings as vanilla as possible! 

[r4w]

Thanks for the response! I do have ntp jail in place, I tried to disable it but with no changes. 

However, I do have two OpenWrt travel routers, I configured one of them to use pppoe and it is working as expected. 

I still can't figure out what is wrong on my main router, I will go and check the network config manually in case there are some leftovers from the previous configuration. 

I am not being lazy but reconfigure it from scratch could be definitely a challenge, leaving it as very last option! 

[r4w · Accepted solution]

Closing the loop on this, my previous Wan configuration was using IPoE aka DHCP as Sky does not use PPPoE like many Openreach providers.
I did switch the Wan to use PPPoE and, while I did not receive any errors and the connection was successful,  I got the weird behaviour that I described where some websites didn't look routed/accessible at all.
The manual review of /etc/config/network showed that the 'wan' interface was mentioned at least two times and also the config was duplicated (I don't remember which one exactly as I had to edit it on my phone).
I removed the wan configuration entirely, reconfigured it from scratch and now it working as expected.
It could be a bug in way the wan is switched between protocols, but I am really unsure at this point.
Posting it here, in case it helps someone else in the future!