Internet connection drops on certain VLAN

[firewalled101]

I am noob at this. I have my network setup as ISP Arrris modem --> OPNsense router/firewall --> network switch --> APs on MESH. I have my network segregated into VLANs each distributed to their respective Wifi. Recently, I note transient internet connection drop outs intermittently on a particular Wifi/VLAN. I do not have stringent firewalls of any sort at least not on this VLAN. The problem happened simultaneously on two devices connected to the same troublesome Wifi, so I do not think this is a peripheral device issue. I am not sure how to troubleshoot this at the level of opnsense or switch. I appreciate some guidance.