certain site/app blocked by the firmware?

[hubn]

I have a RT-AC68U that was running a 380 version. Everything runs pretty smoothly the only problem is that certain Chinese video website and app are not working on my phone. The same website and app works fon my phone when I'm connect to LTE. I always thought it's my ISP's problem until today I got a bit curious and tried a few things. I wasn't able to connect my phone directly to my modem so I couldn't replicate the app problem. But I was able to find the video address and sent it to my pc. I tried the website on my pc browser and got the same problem on my phone, the video spins forever and wouldn't load. Then I disconnect my router from my modem and refresh the page, the video loaded instantly. So the problem is not on my ISP's side. After I found out the problem is on my router, I tried to upgrade the router to the latest firmware, reset the router to factory setting, turned off the router firewall. None of them resolved the issue.

Is there any setting I missed that could block a certain website or is there any log I can check to see what's going on?

 

[RMerlin]

The router does not block anything by default, unless you enable AiProtection features or use the URL filtering. Note however that it's possible your WAN IP address was blocked by the remote site, and plugging the computer directly to the modem simply gave you another IP address that was allowed.

The DNS server used can also have an impact (if you manually use a third party service like OpenDNS).