Error in Microsoft Exchange

Hello. I tried to migrate my entire mailbox to an online Microsoft exchange but got this error instead:

Error: MigrationTransientException: MapiExceptionNetworkError: Unable to make connection to the server. ‎(hr=0x80004005, ec=2423)‎ Diagnostic context: … Lid: 8600 dwParam: 0x6BA Msg: EEInfo: ProcessID: 3260 Lid: 12696 dwParam: 0x6BA Msg: EEInfo: Generation Time: 2018-09-14 20:56:36:406 Lid: 10648 dwParam: 0x6BA Msg: EEInfo: Generating component: 18 Lid: 14744 dwParam: 0x6BA Msg: EEInfo: Status: 10061 Lid: 9624 dwParam: 0x6BA Msg: EEInfo: Detection location: 318 Lid: 13720 dwParam: 0x6BA Msg: EEInfo: Flags: 0 Lid: 11672 dwParam: 0x6BA Msg: EEInfo: NumberOfParameters: 0 Lid: 53361 StoreEc: 0x977 Lid: 51859 Lid: 33649 StoreEc: 0x977 Lid: 43315 Lid: 58225 StoreEc: 0x977 Lid: 50835 Lid: 62321 StoreEc: 0x977 Lid: 47987 Lid: 50033 StoreEc: 0x977 Lid: 52465 StoreEc: 0x977 Lid: 60065 Lid: 33777 StoreEc: 0x977 Lid: 59805 Lid: 52209 StoreEc: 0x977 Lid: 56583 Lid: 52487 StoreEc: 0x977 Lid: 19778 Lid: 27970 StoreEc: 0x977 Lid: 17730 Lid: 25922 StoreEc: 0x977 --> MapiExceptionNetworkError: Unable to make connection to the server. ‎(hr=0x80004005, ec=2423)‎ Diagnostic context: … Lid: 8600 dwParam: 0x6BA Msg: EEInfo: ProcessID: 3260 Lid: 12696 dwParam: 0x6BA Msg: EEInfo: Generation Time: 2018-09-14 20:56:36:406 Lid: 10648 dwParam: 0x6BA Msg: EEInfo: Generating component: 18 Lid: 14744 dwParam: 0x6BA Msg: EEInfo: Status: 10061 Lid: 9624 dwParam: 0x6BA Msg: EEInfo: Detection location: 318 Lid: 13720 dwParam: 0x6BA Msg: EEInfo: Flags: 0 Lid: 11672 dwParam: 0x6BA Msg: EEInfo: NumberOfParameters: 0 Lid: 53361 StoreEc: 0x977 Lid: 51859 Lid: 33649 StoreEc: 0x977 Lid: 43315 Lid: 58225 StoreEc: 0x977 Lid: 50835 Lid: 62321 StoreEc: 0x977 Lid: 47987 Lid: 50033 StoreEc: 0x977 Lid: 52465 StoreEc: 0x977 Lid: 60065 Lid: 33777 StoreEc: 0x977 Lid: 59805 Lid: 52209 StoreEc: 0x977 Lid: 56583 Lid: 52487 StoreEc: 0x977 Lid: 19778 Lid: 27970 StoreEc: 0x977 Lid: 17730 Lid: 25922 StoreEc: 0x977

I know it might be a bit lengthy but it also provides clues that I probably just cannot see…

make sure the port 135 has opened before migrating all the mailboxes