XT12 IP Passthrough DHCPS-fixed

[clinchas]

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 frequency set to Aggressive mode

Issue:
Since upgrading my XT12 to 3004.388.8_2, periodically (sometimes weeks, maybe more) my XT12 WAN IP will become a 192.168.2.x address, which is a small 10 IP address range set on the BGW320-500. I have to have DHCP enabled or else IP Passthrough options become greyed out on the BGW320-500. I could set the BGW320-500 to manual DHCP mode but I worry if AT&T does ever change my WAN IP it will break my internet connection until I reconfigure the XT12 (no different than it randomly breaking my external connections now I guess when the random 192.168.2.x IP issue occurs, internal to external connectivity still works when the 192.168.2.x WAN IP occurs). Reapplying the WAN settings on the XT12 resolves the issue (a WAN address is applied).

 

[Justinh]

Have you tried using DHCPS-dynamic?
Have you tried limiting the BGW's DHCP pool to (1) usable address (...1)?
Have you tried setting the XT12's query frequency to Normal or Continuous?
Does rebooting the BGW correct the situation (in lieu of fiddling with the XT12)?

Could you post a pic of the XT12's WAN - Internet Connection page?

 

[clinchas]

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 it's interesting that the IP passthrough address is a separate line item from the pool line items (second screen shot below).
I initially tried changing the frequency, with same issue.
Didn't try rebooting the BGW instead of re-applying settings on the XT12.

As I mentioned in #1 above, I haven't had the issue again since the post, so I'm hoping it was an issue on the AT&T side. If I do have the issue again I'll try some of your suggestions and post on this thread. Thanks!