DHCPS-dynamic was the initial setting when it was happening, I haven't changed it back to try it dynamic again because (crosses fingers) I haven't had the issue reoccur since my post.
Haven't tried limiting to 1 from the current 10 pool, but this question made me go look at the BGW settings and...
Hoping someone else has seen this and give me some guidance.
Configuration:
Internet Provider: AT&T Fiber with HUMAX BGW320-500 in IP Passthrough mode (DHCPS-fixed)
Internal Router: ASUS XT12 in Wireless router mode / AiMesh Router mode, running Asuswrt-Merlin 3004.388.8_2, DHCP query...