Question: In a roaming scenario, how should a UE construct the Operator Identifier based ePDG FQDN when utilizing services from either the VPLMN (Visited PLMN) or HPLMN (Home PLMN), according to 3GPP standards for non-3GPP accesses?
Option 1: Using only the MNC and MCC of the UE's HPLMN, regardless of the network currently being accessed.
Option 2: Randomly selecting between the MNC and MCC of either the VPLMN or HPLMN for each connection attempt.
Option 3: Constructing two separate ePDG FQDNs, one with the VPLMN's MNC and MCC, and another with the HPLMN's, and then alternating between them.
Option 4: Using the MNC and MCC of the PLMN whose services are currently being utilized (either VPLMN for visited network services or HPLMN for home network services).
Explanation: This is correct because, according to the standards, the Operator Identifier based ePDG FQDN should be constructed using the MNC and MCC of the PLMN whose services the UE is currently utilizing, ensuring proper identification and routing within either the visited or home network for seamless service access in roaming situations.