Vlan help - Extending guest wifi via Vlan to DumbAP

Installing and Using OpenWrt Network and Wireless Configuration
22

Was required to reset MR and AP2 cause wasn´t able to connect.
Means MR and AP2 are back to the config I started with.
AP2 was exactly the same config as AP1 - exeption line list ports 'lan2:t' for VLAN 3 was deleted.

Checked port connections again, the only thing to mention is port 2 on MR isn´t connected yet, means is empty.

Can I somehow go step by step and identify the bug?

AP1 VLAN config is

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 'xxxx'
	option packet_steering '1'

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

config interface 'lan'
	option device 'br-lan.2'
	option proto 'static'
	option ipaddr '192.168.2.7'
	option netmask '255.255.255.0'
	option ip6assign '60'
	option gateway '192.168.2.1'
	list dns '192.168.2.1'

config interface 'wan'
	option device 'wan'
	option proto 'dhcp'
	option disabled '1'

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

config interface 'guest'
	option proto 'none'
	option device 'br-lan.3'

config bridge-vlan
	option device 'br-lan'
	option vlan '2'
	list ports 'lan1:u*'
	list ports 'lan2:u*'
	list ports 'lan3:u*'
	list ports 'lan4:u*'

config bridge-vlan
	option device 'br-lan'
	option vlan '3'
	list ports 'lan1:t'
	list ports 'lan2:t'

and AP3 (as said not yet directly connected)

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 'xxxx'
	option packet_steering '1'

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'eth0'

config device
	option name 'br-guest'
	option type 'bridge'
	list ports 'eth0.3'

config interface 'lan'
	option device 'br-lan'
	option proto 'static'
	option ipaddr '192.168.2.9'
	option netmask '255.255.255.0'
	option ip6assign '60'
	option gateway '192.168.2.1'
	list dns '192.168.2.1'

config interface 'guest'
	option device 'br-guest'
	option proto 'none'