Yes, with VLANs and managed switches. But if you don’t already have managed switches, you’d have to replace both of them. By far the cheapest solution is to put a small wired router (e.g. I’ve owned a TPLINK ER605 that would work, performing routing and DHCP) between the ONT and SW1, and then reconfigure the WiFi-Router to turn off the router and DHCP functions, leaving the internal switch functional and allowing the WiFi to serve as an Access Point.
Yes, with VLANs and managed switches. But if you don’t already have managed switches, you’d have to replace both of them. By far the cheapest solution is to put a small wired router (e.g. I’ve owned a TPLINK ER605 that would work, performing routing and DHCP) between the ONT and SW1, and then reconfigure the WiFi-Router to turn off the router and DHCP functions, leaving the internal switch functional and allowing the WiFi to serve as an Access Point.