EPIC 対策パッチかな
multihome にしていると EGS はローカルIP見にいってしまうから、接続IPを強制的に指定しろってことかな

Current Version: v312.13 - 06/26/2020

New command line arg: -PublicIPForEpic=<IPAddress>
If this command line arg is used, this is the public IP that EGS clients will attempt to connect to.
If this command line is missing and -Multihome is specified, then EGS clients will attempt to connect to the Multihome IP
Note that if you're using Multihome and specify a non-public IP address, then players will not be able to connect to your server using EGS. Make sure to set a public IP address (e.g WAN or external)