It's either the business that's administrating the wifi has blocked firearm related websites, or the IP of your VPN has been blocked by If you turn off your VPN and you're still blocked, you know it's the wifi administrator that's blocking this website; otherwise, KahrForums is blocking your IP address. Most likely, you're using a free or shared VPN, which has been banned in the past.

When I'm on my job's wifi or on the wifi at Taco Bell, Wal-Mart, at the hospital, and other places, all firearm related websites will be blocked unless I turn on my VPN. Sometimes, when I use free or shared VPNs, some websites would have the IP address of the VPN I'm using blocked.