I am experiencing the exact same issue with a Nitrado server… all of the players on the server need multiple attempts to get in…and sometimes can not get in at all especially during peak hours. I believe the log file below is capturing the issue:
[2020.07.09-00.17.08:651][687]LogDreamworld:Display: PreLogin: XXXXXXXX
[2020.07.09-00.17.08:651][687]ConanSandbox:Display: User XXXXXXXX logged in from unknown country
[2020.07.09-00.17.08:651][687]LogOnline:Warning: STEAM: Steam API disabled!
[2020.07.09-00.17.08:651][687]LogOnline:Display: STEAM: OnlineSubsystemSteam::Shutdown()
[2020.07.09-00.17.08:651][687]LogNet: Client login from xx.xx.xx.xx, with ping 60
[2020.07.09-00.17.08:683][688]LogFuncomLiveServices:Error: VerifyIdentity Failed: Request Timeout or null response
[2020.07.09-00.17.08:687][688]LogNet: UNetConnection::Close: [UNetConnection] RemoteAddr: xx.xx.xx.xx:52309, Name: IpConnection_27, Driver: GameNetDriver IpNetDriver_0, IsServer: YES, PC: NULL, Owner: NULL, Channels: 1, Time: 2020.07.09-00.17.08
[2020.07.09-00.17.08:688][688]LogNet: UChannel::Close: Sending CloseBunch. ChIndex == 0. Name: [UChannel] ChIndex: 0, Closing: 0 [UNetConnection] RemoteAddr: xx.xx.xx.xx:52309, Name: IpConnection_27, Driver: GameNetDriver IpNetDriver_0, IsServer: YES, PC: NULL, Owner: NULL