For me, this issue is intermittent but happens a lot and happened on both Catalina and Big Sur. Sometimes it will affect both Ethernet and WIFI or sometime only the WIFI. My colleague and I figured is that if we kill vpnagentd and restart the affected network interfaces, that it will help bring them back without having to restart the Mac. If it helps anyone, here's the bash script that I crafted that serves as a workaround for this so you won't have to reboot:
#!/bin/bash
function restartNetworkInterfaces()
{
net_interfaces=("$@")
for net_interface in ${net_interfaces[@]}; do
echo "Restarting interface: ${net_interface}"
sudo ifconfig ${net_interface} down
sudo ifconfig ${net_interface} up
ifconfig -u ${net_interface}
done
}
VPNAGENTD="/opt/cisco/anyconnect/bin/vpnagentd -execv_instance"
echo "Restarting ${VPNAGENTD}"
sudo pkill -9 -f ${VPNAGENTD}
ETHERNET_INT=`networksetup -listnetworkserviceorder | sed -En 's|^\(Hardware Port: .*Ethernet.*, Device: (en.)\)$|\1|p'`
restartNetworkInterfaces "${ETHERNET_INT[@]}"
WIFI_INT=`networksetup -listnetworkserviceorder | sed -En 's/^\(Hardware Port: (Wi-Fi|AirPort), Device: (en.)\)$/\2/p'`
restartNetworkInterfaces "${WIFI_INT[@]}"Another scenario which I felt is related to this is that my MAC will just auto reboot because of a panic from waking up. Did anyone experience this too?
