I'm assuming you have a 2016. There could be many issues. Unfortunately this problem is too common but fortunately many interventions can solve it as well. Things to try:
Reboot the Apex.
Reboot your cable modem, gateway, and/or router.
Check and update firmware on all Apex modules. (In particular, reinstall the Cor module firmware even if reading OK.)
Plug the EB832 into a UPS for cleaner system power.
Install a plug-in WiFi extender and connect the Apex to its network rather than the base network.
One of those will fix the problem most of the time, in my experience.
Next step would be a getting a ticket in to Neptune support; there could be an undiagnosed hardware or software issue.
Although if all else fails (and sometimes it does), there's always the new router route which sometimes like a miracle corrects everything (my recent personal experience with a home network of 46 devices controlled by a router that was becoming demented, although no problems directly related to my two Apex controllers.)
