First I want to say thanks to all who worked on getting the Linksys MX4300 supported. I finally have 99% of the functionality I was looking for. I tried using some of the early releases but encountered some issues and decided to wait for full support. I bought several MX4300s during the Woot/Amazon special with the hope that in the not too distant future I would be able to take advantage of the great price. I use a repurposed PC for my pfSense router/firewall, connected to smart switch and then used several old routers I had in the attic as AP's but weren't in the table of supported devices for OpenWRT. Each old AP was on a different VLAN and configured with a single SSID. Each AP was placed in strategic spots around the house. There were several areas of the house where certain SSIDs had weak signals. Now with OpenWRT I was able to configure the MX4300's with multiple VLANs and each of the SSIDs assigned to a specific VLAN. Now with the distribution of the APs I get full signal for each SSID. One AP required a cable run that I couldn't hide in the walls. Was looking to use wireless backhaul for that one. Is it possible to mix/match wired and wireless AP? I considered trying B.A.T.M.A.N. but so far I am having difficulty following the video I found. If someone has a good video I may have missed, please share. It's a work in progress for me.
It’s certainly possible to have both wired and wireless AP. In your use case, you just need a single wireless bridge. It’s not necessary to use mesh or batman for that. Relayd will work just fine:
[OpenWrt Wiki] Wi-Fi Extender/Repeater with relayd
Transform a Cheap Used Router into Wireless Extender (No Cables) | OpenWRT - YouTube
Thanks for the response. Will check it out and see how it goes.
Please correct me if I am mistaken. But after reviewing the video/article you posted, this is only extendeding one SSID wirelessly. I was looking at using a wireless backhaul to pass all my vlans and then present all the SSIDs on the wireless node just like I do with the other APs.
Thanks.
I believe this just creates a wireless backhaul as a substitute for a wired one. You can then configure multiple SSIDs on that AP in the same manner as you do the wired ones.
You might be able to create multiple SSIDs on the one wireless interface, but I don't believe you can map to seperate VLANs with this method. I have been reading up on VLAN tunneling with wireless connection on OpenWRT and GRE or alternatively B.A.T.M.A.N. There are some videos (by Onemarcfifty) on the subject but I was having difficulty with some of the steps.
That thread seems to be similar to what I would like to do. Only difference is I have multiple access points already connected to the switch and just need one of them to extend the VLANs wirelessly. After parsing through the post I see some different approaches but then someone actually recommending B.A.T.M.A.N. as the better option. Which is what I was originally trying to do but with difficulty. Maybe when I have some free time again I can approach it fresh again and see if something clicks 
Thanks.
Yes you can have multiple vlan ssid on batman using then same wifi radio. I have this. I created, for now, 2 vlan ssid that is using 2.4 ghz radio. One is used for my esphome devices and other is for my cloud needee things. But you can add as much as you want.
But for now my valn ssid is created on asus ax88u that i bought before or in just a time starting with openwrt. This router is used as gateway and is waiting to be replaced with something better like mini pc running opensense.
If you need some config i can past you my config files. It’s totally doable and is not that hard. Much harder is to fine tune batman network over wifi.