Use WAN port as LAN

What are the (correct) steps to use a WAN port as standard LAN? I need another port on the cheap, and already have another device upstream to my AP doing the routing so don't need a dedicated WAN port.

I thought a simple bridge between LAN to WAN would have done the trick, so I added WAN/WAN6 (eth0 on my device) to the default bridge (br-lan, so the one between LAN and WLAN), but after doing that pings still fail to a device connected via Ether to the WAN port. I have verified that the device responds to pings when I directly connect via Ether without the AP (the downstream device I'm wanting to plug into the WAN port is another switch so I've done this ping test with my laptop and simple patch cable directly connected).

Next, I thought the default VLANs that separate LAN from WAN were the problem, so I flattened the Switch to a single VLAN (deleted VLAN_ID=2, so only VLAN_ID=1), but that caused all connectivity to my AP to stop. :frowning: I ended up having to re-flash OpenWRT via TFTP and restore from backup to get connectivity to my AP.

All I'm looking to do is connected a device to the WAN port and have it communicate with the standard LAN ports, so what am I doing wrong?

My AP is: TP-Link AC1750 C7 v2 running OpenWRT v19.07.2

A C7V2 running as an AP with master

config interface 'loopback'
	option ifname 'lo'
	option proto 'static'
	option ipaddr ''
	option netmask ''

config globals 'globals'
	option ula_prefix 'fdee:43c3:9be0::/48'

config interface 'lan'
	option type 'bridge'
	option force_link '1'
	option ifname 'switch0.1 eth1'
#	option ifname 'eth1.1 eth0'
	option proto 'dhcp'
	option ip6assign '60'
#	option proto 'static'
#	option ipaddr ''
#	option netmask ''
#	option gateway ''
#	option dns ''

#config interface 'wan'
#	option ifname 'eth0.2'
#	option proto 'dhcp'

#config interface 'wan6'
#	option ifname 'eth0.2'
#	option proto 'dhcpv6'

config interface 'lan6'
	option proto 'dhcpv6'
	option ifname '@lan'
	option reqprefix no

config switch
	option name 'switch0'
	option reset '1'
	option enable_vlan '1'

config switch_vlan
	option device 'switch0'
	option vlan '1'
	option ports '0 1 2 3 4 5 6'
#	option ports '1 2 3 4 5 6 0t'
#	option ports '2 3 4 5 0t'

#config switch_vlan
#	option device 'switch0'
#	option vlan '2'
#	option ports '1 6t'

It's best to keep it worth a static IP. That make s solving issues either without the need for a DHCP server.

Thx for the quick reply, and sending your config.

I agree that it is best a static IP, but choose to manage all my static IPs at a single point, that being the DNS/DHCP server for my infrastructure.

That't certainly up to you, but say you have an issue with your main router. you won't be able to access the AP (and that can in turn prevent you form accessing any other devices on the network.

I tend to use static leases for all my devices for the same reasons you mentioned, except routers and APs (and possibly servers if I have any); these are significant devices that should have their IPs fixed regardless of anything else.