I observed the similar issue with Monterey and latest Cisco VPN. Simplest solution was to restart the machine, but I was running a critical process on my machine for multiple hours and didn’t wanted to loose that time, so I did a hack to make it work, it’s little disruptive but did the job for me. I tried to get the list of network interface : scutil --nwi there was a demon virtual network interface created by cisco vpn and I cleared that one using scutil utility sudo scutil remove State:/Network/Service/com.cisco.anyconnect/IPv4 this restored the internet connectivity and DNS resolution. I had to re-install Anyconnect to enable vpn but I was able to restore Internet connectivity without restart. I am not sure how generic this solution is but I thought it’s worth sharing. Cheers!