Merlin 384.18 on RT-AC86U - Saved changes to the WAN page break the DNS part of the internet connection

[stagger321]

Hiya.
Recently been trying to resolve DNS connection issues on my main PC.
Yesterday evening I changed the RT-AC86u's 'Connect to DNS server automatically' on the 'WAN' page to 'No' and I specified a couple of DNS servers. Then saved the page.
This stopped the internet from working. I was getting DNS issues when I tried to troubleshoot the PC connection - for the LAN adapter, plus all the other devices on the network stopped working.
I tried many things, including turning my VPN client config off, rebooting the router - several times, everything.
I could get to the router OK, but not anywhere outside.
Fortunately I had a saved router config from February, and reloading this got me back again.
I had to re-enter all my VPN client stuff, (as I have changed VPN since then), so it was a faff, but It was working.
This morning, I saved this new working setup to a new router config file and tried again.
Same result. Stuffed Internet connection.
But, I thought, thats OK, because I have this new saved config file.
Importing this - did not fix it . I had to go back to the old February file.
Has anyone else had issues with the WAN page on save, or reimported CFG files not working.???
Cheers.
Stagger

 

[L&LD]

What DNS servers are you specifying?

 

[stagger321]

Makes no difference. Tried a couple including the Google ones (8.8.8.8, 8.8.4.4). The issue is once you have made the change and saved the page, it buggers up the config. If you the undo your changes and go back to the Automatic option and save the page, which did work before the changes, now it doesn't, and I can only fix it by reimporting that very old config file from Feb.

 

[L&LD]

Unless a very specific fix is available for this issue, it sounds to me that your router needs a full reset to factory defaults and then minimal and manual configuration (i.e. this isn't normal operation).

 

[stagger321]

Thanks. Will bear this in mind.
I'd rather not do this unless necessary as I have the Asus router running piggyback from my Talktalk ISP's Huawei modem router which is running in modem-only mode, and has been since I first bought the RT-AC86U a couple of years ago.
It took ages to get the config right for both these boxes, so I don't really want to go through that again.
Bit odd that its gone awry like this as the WAN page has been untouched for ages. Saves on the other panels seem OK, just the WAN page.
I may see what happens the next time I do the next released Merlin firmware upgrade.