Apologies for the naivety of the question. I have a TP-Link R600N VPN Wired Router which acts as my main Router and WAN manager. Right now I have 3 different Wireless APs (TP-Link Archer A6 v3, Xiaomi 4A Gigabit & Xiaomi 4C) which only act as access points and have DHCP disabled.
I still want to continue with the same arrangement that is my Wired Router R600VPN as the main router handing IPs to all devices whereas all wireless APs will run OpenWRT but in mesh mode. I have already installed OpenWRT on Xiaomi 4C and have played around with the UI to get some understanding.
So the question is can I run all three APs in so-called "DUMB AP" mode and still have mesh functionality?
That depends on what you understand under the term "mesh"…
What is usually/ traditionally understood as meshing, would be multiple satellites self-organizing a network over wireless interconnects, dynamically reconfiguring as mesh stations come and go, dealing with multiple uplink routes to the network. Keywords for this would be IEEE 802.11s or B.A.T.M.A.N., but if all of your dumb APs already have a wired uplink to your router, you don't need any of these.
What the industry is marketing as mesh systems these days is rather different from the traditional definition. While expectations aren't quite clear cut there either, they usually imply central management of their satellite fleet (configuration, firmware updates, etc. - similar to the task of a wireless controller in professional AP gear) and dynamically switching between wired- and wireless backhauls (albeit usually not to the extent of real mesh systems like 802.11s) using proprietary protocols.
If you already have wired connections for all your dumb APs, there is nothing to gain from meshing here - you already have the best possible backend infrastructure (ethernet) for your APs. While OpenWrt won't provide you central management (wireless controller) features at this moment, but you can still optimize cooperative roaming between your APs via IEEE 802.11r/v/k and even use DAWN or usteer for bandsteering and coercing your clients to make the 'right' roaming decisions.
Thanks, @slh for your explanation. My apologies I missed adding some information that is relevant. I am indeed referring to 802.11s while talking about mesh.
I have loads of devices like 10+ Echo & Google Home devices, a bunch of Smart Bulbs, ESP8266 devices connected to HomeAssiatnt via WiFi but these are always in a fixed position so no issues here.
My main issue is when I move from downstairs to upstairs my mobile devices (Phones, Tab, Laptop) don't switch to the upstairs AP even though with the same SSID and password. Needless to mention that connection becomes very weak but these devices still won't disconnect I am currently reading through and planning to at least try 802.11r fast roaming and take your suggestion to explore DAWN and usteer to force devices towards better connections.
Just one question though - In this scenario how would 802.11s and 802.11r differ?
So that's where 802.11k and 802.11v come in. They can be used to understand how well a device can see the various APs, and tell it to move to a better one if the controller believes it is worthwhile.
For DAWN (currently in testing, so not "off the shelf" yet) this means a blend of two things:
As a device passes a certain absolute threshold (-65dB by default) it will be given a list of APs to consider moving to (but no enforcement), and most 802.11v enabled devices will do so.
If a device is sitting somewhere that it doesn't quite hit that threshold (eg -63dB) but there is a noticeably better AP availabile (eg -50dB) it will be "strongly encouraged" to move to it.
802.11r is not directly involved in the transition suggestion. It's role is to make the switch from one AP to the other much faster - practically invisible to many applications.
802.11s is quitre seperate. It is about how a bunch of APs dotted around a house or campus would organise themselves to transfer data to the outside world by wireless transfer from one to the other, not how clients would select APs. As stated above, if you have wired connections from each AP to the gateway you don't need that wireless hopping.