notwithstanding ntop's non-supportive moves wrt the ntopng plugin, if anyone is having odd periodic WAN and/or LAN losses and is running ntopng with active network discovery, it can be solved by turning off ntopng active network discovery or by going to your opnsense web-interface->services->ntopng->settings and setting interfaces (may need to click advanced) explicitly to EXCLUDE WAN (i.e. add any interface but WAN. Or remove ntopng :D.
This seem to be the solution for ntopng community from opnsense or if you install via ntop's repository.
This seem to be the solution for ntopng community from opnsense or if you install via ntop's repository.