ASUS RTAX-86U issue with DNS

[zillah]

Dear Experts

I have got an ASUS router RTAX-86U with latest Merlin firmware I was using below static DNS (I forgot why but I guess because I have been using NORD VPN I changed it from ISP's DNS to static one)
9.9.9.11
149.112.112.11
Recently I had an issue with couple of websites not all say : can't be reached ,,,,,once I changed DNS from static to ISP one issue fixed.
Does that mean it is better to use always ISP's DNSs ?

 

[bennor]

Does that mean it is better to use always ISP's DNSs ?

It may help if you further explain your router's DNS configuration and if you are running any addon scripts like Skynet or Diversion, or are using a DNS sink hole like Pi-Hole on the local network.
What firmware is the router running?
What do you have configured for the WAN DNS Setting?
What do you have configured for the LAN > DHCP Server > DNS and WINS Server Setting?
Did the issue happen across multiple devices on your local network?

Its entirely possible that there was just a temporary routing problem with accessing a website at the time you were trying to access it using Quad9's DNS servers versus using your ISP's DNS servers.