Remote Gateway IP field

[bluerains]

does the client who connect to PFsense IPsec need static IP then?  Couldn't PFsense use username/password to authenticate?  If it could, what do I put in the remote gateway field?

Thx

[cmb]

The section you're referring to is for site to site VPNs. Those either require a hostname or IP for the remote. For mobile clients, you want mobile IPsec which is separate.