Why does my DNS time out on Gentoo and does not resolve?

DNS for a Gentoo box is not working. In order for it to work, I have to add 8.8.8.8 to dns_servers_br0, and even then it only works for what seems about 5 minutes before I have to restart the net.br0 interface to get DNS working again (and only when 8.8.8.8 is included as a server). It sits behind a pfSense router running Proton VPN using WireGuard and is managed by netifrc.

Below is my /etc/conf.d/net file.

tuntap_tap0="tap"
config_tap0="null"

tuntap_tap1="tap"
config_tap1="null"

tunctl_tap0="-t tap0 -u me"
tunctl_tap1="-t tap1 -u me"

# Configure to null so DHCP does not get started.
config_eno1="null"

# Configure bridge.
bridge_forward_delay_br0=0
bridge_hello_time_br0=1000
bridge_stp_state_br0=0

# Setup initial layer 2 bridge interface.
bridge_br0="eno1 tap0 tap1"

# bridge static config
config_br0="192.168.120.10 netmask 255.255.255.0"
routes_br0="default via 192.168.120.1"

# I have to add 8.8.8.8 here to make DNS work.
dns_servers_br0="192.168.120.1"
dns_search_br0="home.arpa"

depend_br0() {
    need net.eno1
    need net.tap0
    need net.tap1
}

My box is the 120.10 address and the pfSense router is 120.1. My /etc/resolv.conf (regular file) appears as:

search home.arpa
nameserver 192.168.120.1

And possibly some other helpful information:

$ arp -a
pfSense.home.arpa (192.168.120.1) at 00:e2:69:6c:cf:fd [ether] on eno1
pfSense.home.arpa (192.168.120.1) at 00:e2:69:6c:cf:fd [ether] on br0

$ nslookup google.com

;; Got SERVFAIL reply from 192.168.120.1
Server:         192.168.120.1
Address:        192.168.120.1#53

** server can't find google.com: SERVFAIL