I haven’t been able to get the hard travel to work without the players disconnecting from the server when ServerTravel is called. Maybe I’m doing something wrong, is it possible to use the hard travel and keep players “connected” to the server? Seamless travel is working fine for me (apart from the online beacon problem, but I suspect seamless travel is not the culprit here), although being able to use a hard travel would be better for me since I’d feel more safe about my game state properly resetting after a new map load.
About my issue, it seems something wasn’t being applied correctly. The issue seems to come from bUseSteamNetworking set to true. Switching it off (that is, not using Steam Sockets at all) and using the IpNetDriver for the beacon appears to fix the issue. So I suspect the problem is caused by trying to use online beacons with the Steam Sockets plugin and bUseSteamNetworking set to true.