The network config seems suspect, an example of some of that which is current:
/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 'fde2:1857:9a33::/48'
option ula_prefix 'auto'
option packet_steering '1'
config device 'wan_wan_dev'
option name 'wan'
option macaddr 'xx:xx...'
config interface 'wan'
option device 'wan'
option proto 'dhcp'
config interface 'wan6'
option device 'wan'
option proto 'dhcpv6'
config device
option name 'switch0'
option type 'bridge'
option macaddr 'xx:xx...'
list ports 'lan4'
list ports 'lan3'
list ports 'lan2'
list ports 'lan1'
option igmp_snooping '1'
option vlan_filtering '1'
option stp '1'
### STP gens an error in dmesg ###
config bridge-vlan
option device 'switch0'
option vlan '10'
list ports 'lan4:*'
list ports 'lan3:*'
option alias 'lan'
config interface 'lan'
option ifname 'switch0.lan'
option proto 'static'
option ipaddr '192.168.10.1'
option netmask '255.255.255.0'
option ip6assign '60'
config bridge-vlan
option device 'switch0'
option vlan '20'
list ports 'lan2:t'
list ports 'lan1:t'
option alias 'ap'
config interface 'ap'
option ifname 'switch0.ap'
option proto 'static'
option ipaddr '192.168.20.1'
option netmask '255.255.255.0'
option ip6assign '60'
config bridge-vlan
option device 'switch0'
option vlan '30'
list ports 'lan2:t'
list ports 'lan1:*'
option alias 'iot'
config interface 'iot'
option ifname 'switch0.iot'
option proto 'static'
option ipaddr '192.168.30.1'
option netmask '255.255.255.0'
option ip6assign '60'
config bridge-vlan
option device 'switch0'
option vlan '4094'
list ports 'lan2:t*'
option alias 'sink'
config interface 'windscribevpn'
option ifname 'tun0'
option proto 'none'
root@mamba:/etc/config# bridge vlan
port vlan-id
lan4 10 PVID Egress Untagged
lan3 10 PVID Egress Untagged
lan2 20
30
4094 PVID
lan1 20
30 PVID Egress Untagged
switch0 10
20
30
4094
root@mamba:/etc/config# brctl show
bridge name bridge id STP enabled interfaces
switch0 7fff.94103e85b525 yes lan4
lan2
lan3
lan1
just example from me testing things here, so... Also, this is from a very recent master, I'm not sure if the version you are on has the requisite netifd changes for some of that syntax; there has been a lot of changes coming down the pipe as of late.