If acceptable, I would build an option into the Config mode, that sets all ports to WAN, so it doesn't matter any more on which port you connect the node with your internet.
In most places nobody needs the LAN ports to get direct Freifunk via LAN, but the most asked question I get is "On which port do I have to connect"? Also this is a commmon mistake that new users make, to mix up the ports.
Sure, if not needed you can already set this setting on the console with:
uci set network.client.ifname=bat0
uci set network.wan.ifname='eth0 eth1'
uci commit network
Source: https://wiki.freifunk.net/Konsole#WAN_auf_allen_Netzwerkports
I would appreciate there was a way to set this such that it works across upgrades.
I once had a hacky gluon-luci package for creating that setting, but since this depends on the hardware model and switch configuration there was only an implementation for tl-wr841 and tl-wdr4300. The solution was so nasty I don't even dare to link it here.
Quite a while ago someone mentioned that with a new network configuration infrastructure this could be resolved in a proper way. Is there a roadmap (not in terms of timeline but in terms of the necessary steps) for this already? If not, can we develop & discuss it here?
I would greatly appreciate that option.
It would help to integrate routers into existing setups without free ethernet ports.
It is also a good argument for some people that need a switch somewhere in their growing home network to use a gluon-router instead of a switch.
Actually it would be great, if you could configure the ports like in a table. And those settings should be kept over upgrades.
I've made a little mock-up:

Maybe a button could also be included to create VLAN IDs on the ports to carry two or more of the network types.
Such a port table would be great. But if I had to choose between:
I personally would prefer the first option. I would know of very little occasions where the above mentioned setup is required. The only setup that I need frequently is Offloaders with WAN/Client/Mesh on a single NIC with 3 VLANs (or 2 NICs with 2 VLANs on the second NIC). Neither setup is trivial to implement in the GUI.
furthermore, the advanced solution is impossible for many devices. on many, the 4 switch ports appear as a single port to the OS.
even on those devices it would be nth to setup multiple bat ifs on different Vlan ids. (off course we can do this manually via /etc/config/, that is out
I think its an really good idea and i am waiting for this for years. Why was this not added from the beginning?
I usually switch the interfaces around, since its easy to do and i still have the option to connect a client (pc or a router) over the WAN port. But yeah its really annoying to undone and redo this change for every update.
I think it would be nice to add options so that you can choose what the two interfaces (WAN Port/Lan Switch) are doing and then maybe set it to bridged (all interfaces to WAN/LAN) by default. A separation for every single port would be cool but maybe a but overkill and not as easy to implement.
Here as an example:

Why was this not added from the beginning?
Because there was a hackaton for this ("port based lan function"), but the results never surfaced (as far as i know).
perhaps some people are hoping that it might still be rectreived.
other arguments are:
(this how i understood it)
The feature will definitely be implemented. There are two reasons this has not happened yet and is not on a short-term roadmap:
There is still some preparation necessary in OpenWrt: AFAIK, there is no DSA-capable driver for the ag71xx Ethernet yet, and the migration of ar71xx to device trees (new target ath79) should be dealt with first.
There is a plan to migrate the current swconfig-based network configuration to DSA (Distributed Switch Architecture) in OpenWrt, which will expose each switch port as a separate network interface.
How far is this probably in the future?
Most helpful comment
Actually it would be great, if you could configure the ports like in a table. And those settings should be kept over upgrades.

I've made a little mock-up:
Maybe a button could also be included to create VLAN IDs on the ports to carry two or more of the network types.