The same Gateways can be used by all users (employers, contractors, third parties), both remote (home / cafe / road-warrior) and local (branch / DC user). With ZTNA all default user trust can be removed and all users can be viewed as “external” users even if they are “on-net”.
The Gateway is hardened to reduce risk of DoS attacks from external, untrusted networks.
Gateways use multiple inputs to verify then trust; and keep on verifying.