Can't access a specific website

Hello community. I have an issue going on where I try to access a specific website and i simply cant. I have double checked all the peplink configuration and it is open to outbound connections by default. The website I am try to access is
I can access it from any other outside but not from my client internal network

When checking the Peplink configuration, is the WAN configured as a static IP address? If so, have you confirmed the subnet mask is correct?

Yes. It is configured with static IP address and we are using the subnet mask provided by the ISP, in this case, with 5 usable IPs. The only website with issues to access is this one

Good to know this for troubleshooting. Does DNS resolution work OK for this site? Google resolves to IP address.

You can also do a traceroute from the router under: System> Tools to find out more.

Is it just one device behind the router or multiple devices?

If the site is accessible from other public IP addresses, then they may be blocking your public IP address on purpose. Perhaps the last person using your public IP abused something. You can test by trying to access the site using a VPN or Tor to change your public IP.

Don’t bother with pings, they seem to be blocked.