When I tried to connect to the customer's VPN using our internet here in the office, the transparent tunneling in the VPN status says Active on UDP 4500. But when I tried connecting to the VPN via Vodafone vodem, the transparent tunneling still shows inactive. Would you know the explanation for this?
Patricia, the fact that your vpn connection is established over UDP 4500 or not depends on whether nat is found on the path, within the IKE negotiation while exchanging the messages there is a point where both vpn peers check the hash of each end and compare it. If it does not match the connection switches to NAT-T (UDP 4500) if there is no nat/PAT along the path then this does not switch.
So correct me if I am wrong you are saying that when using the Vodafone modem you see the transparent tunneling as inactive? if this is the case then it might be normal since your modem might give a public ip address to your modem connection. Are you having any issues with this?