What if an event from the client gets lost

I’m not very expert about the communication linking the server to the client so I’m asking here.

I have the feeling that under some unknown conditions an event from the client gets lost i.e. never reach the application or, at least, the event don’t gets handled.

Both parties, server and client, are connected by an unreliable link i.e. the network so I must presume that error conditions can happens.
I don’t know what can happen in this case.
The browser is able to retry the transmission and/or the framework gets notified of the condition so a resend can be done?

If this it’s not the case, there is something that can produce a failed TriggerServerEvent with no notification to the server and/or locally to the client?