Secondary LAN OpenWrt router occasionally stops routing for no apparent reason

Installing and Using OpenWrt Network and Wireless Configuration
7

So I've introduced a second dnsmasq instance. And promptly moved to configure the second OpenWrt device to purely act as AP. But it's not working, I do not understand why. The metric I'm using to quickly check for connection is if the rent interface is getting IP via DHCP—it does not. lan interface via VLAN 10 is still working fine.

Here's the current config:

# cat /etc/config/network

config interface 'loopback'
        option device 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fdb6:11f4:7509::/48'
        option packet_steering '1'

config device
        option name 'br-lan'
        option type 'bridge'
        list ports 'wan.10'

config interface 'lan'
        option device 'br-lan'
        option proto 'dhcp'

config interface 'wan'
        option proto 'none'
        option disabled '1'

config interface 'wan6'
        option proto 'dhcpv6'
        option disabled '1'
        option reqaddress 'try'
        option reqprefix 'auto'
        option norelease '1'

config device
        option type 'bridge'
        option name 'br-rent'
        list ports 'lan1'
        list ports 'lan2'
        list ports 'lan3'
        list ports 'lan4'
        list ports 'wan'

config interface 'rent'
        option proto 'dhcp'
        option device 'br-rent'
        option hostname '*'

config device
        option type '8021q'
        option ifname 'wan'
        option vid '10'
        option name 'wan.10'

Removed the wan port from wan interface and added it to the br-rent bridge. Enabled DHCP on rent interface to test connectivity.

# cat /etc/config/dhcp

config dnsmasq
        option domainneeded '1'
        option boguspriv '1'
        option filterwin2k '0'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '1'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option nonegcache '0'
        option cachesize '1000'
        option authoritative '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
        option nonwildcard '1'
        option localservice '1'
        option ednspacket_max '1232'
        option filter_aaaa '0'
        option filter_a '0'

config dhcp 'lan'
        option interface 'lan'
        option start '100'
        option limit '150'
        option leasetime '12h'
        option dhcpv4 'server'
        option dhcpv6 'hybrid'
        option ra 'hybrid'
        list ra_flags 'managed-config'
        list ra_flags 'other-config'
        option ignore '1'

config dhcp 'wan'
        option interface 'wan'
        option ignore '1'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'
        option loglevel '4'

config dhcp 'rent'
        option interface 'rent'
        option start '100'
        option limit '150'
        option leasetime '12h'
        option ignore '1'

Disabled DHCP on the rent interface.

PS How do I monitor for activity when OpenWrt is configured as AP? Bandwidth realtime graphs?
PPS I've chosen for DHCP client on the rent interface for testing. If everything is working as expected, setting it to unmanaged protocol should be fine, correct?