DHCP problem?(when increase static lease count, entire system going down/hang)

Hi.

When I set static lease in the dhcp section(via UI or console both),
entire system going down(at the certain point extreamly slow with 6 items, and system going down when adding more). only way to recovery is Hard reset by pressing the tiny reset button on the H/W(OpenWRT 19.07.7 with all upgrade + dnsmasq-full on Linksys WRT32X).

If there any limitation on dhcp deamon?
Is there any....interruption by mac address pattern or client rssi strength, or whatever thing?
What am I missing?

Make sure not to use duplicate MAC addresses.

Checked and
there is NO dupl MAC, NO dupl IP, No dupl name at all since I manually consolidate the /etc/config/dhcp file.

(If there is dhcp and dnsmsq-full and network source maintainer to investigate, I can provide the config file privately(since all mac and ip and names).)

If possible, check the system log for errors.