My dropbox is no longer syncing files,

Hello,

The best way to start is to make sure that F-Secure is indeed the cause of Dropbox not syncing files.

Let's assume that this is the case, then perhaps some resource / domain is being blocked by F-Secure. If so, there could be some reasons - perhaps the use of Family Protection functionality, a false positive blocking as harmful or malicious, or something like a firewall sensor (an option in Device Protection settings). You could try disabling them. Then, for example, clear / reset the reputation cache and compare the situation (perhaps with a system reboot).

Otherwise, can you add more information? For example, did the problem appear suddenly? Or did something change - Dropbox updated or F-Secure upgraded?

Thanks!