Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I suspect that the firewall on the Dell laptop may have cut off communication on the network port required for the syncing.
Or, perhaps, the syncing process has failed on the laptop.
(Why the laptop? I'm not sure... but the question could be settled more surely, if you look on the main account, the server side of the meetings or appointments, which is supposed to sync with the two local devices, and see whether the Note 4, or the Dell laptop's, changes are syncing with it.)
(Unless, of course, you set up syncing to go directly between the laptop and the Note 4... in which case the laptop is still a reasonable place to start.)
Let me know more about how the syncing is supposed to work, and I will advise you further.
In order to give good instructions in detail, I will need to know, please:
1: what are you trying to sync? the Appointments, and the Calendar ? from Office 365 ?
2: where are you trying to sync them? to a server online? if so, what server, Google, Cloud, other?
OK, I see.
What Calendar app do you use? is it perhaps Google Calendar? or some other?