Situation: the client WFH and access company private websites through VPN. Now, he can’t access some of websites inside.
Troubleshooting: 1. He can’t use Microsoft Edge and google Chrome to access those websites. However Firefox works fine.
2. He has clear the cache on both Edge and Chrome.
3, finally, we find IT enabled DNS over HTTPs recently on their firewall. Disable DoH fixes the problem.
