Troubleshooting Website Access

If some sites will load, but other sites will not, there are a few possible causes.

  • Check all of the items listed on Connectivity Troubleshooting before proceeding

  • Ensure the WAN gateway is reachable and set to the proper address

  • Ensure the subnet mask on the WAN interface of the firewall is correct

  • Ensure the subnet mask on the client stations and on every interface (and VPN) in the pfSense® software configuration is correct

  • Ensure the WAN MTU is properly set (See to determine the MTU), use MSS to lower the MTU if necessary

  • Use traceroute to determine where the traffic stops. It may be an upstream connectivity issue and not the firewall or ISP.

  • Disable hardware checksums and see if the problem disappears

  • Disable any proxy package such as squid that is in use (if any)

  • Check Clear invalid DF bits instead of dropping the packets on System > Advanced, Firewall/NAT tab.

  • Check Disable Firewall Scrub on System > Advanced, Firewall/NAT tab.