As a followup to my previous post, I tried downgrading DDWRT to firmware version DD-WRT v3.0-r36527 std (08/09/18) and the issue was resolved. Thought this might be useful for anyone else with TPLink...

@thevilla I am having the exact same problem. My router is an ASUS RT-AC3200 flashed with DD-WRT v3.0-r40559 std (08/06/19). I have an IOT VLAN (which is on a virtual wireless network), and if I...