WDS 5GHz for linking APs / 2.4GHz for clients

recently i set up 2x Archer C7 v4 as WDS followed the atherosWDS tutorial. it is up and running well. i use them for smart-home devices so the APs run on bgn while the 5gHz radios disabled.
the bandwith was not a concern till now due to only short commands passing between devices but i think about improve the system performance for general web-use.

is it possible (i guess so) to utilize the ac radios to connect the 2 routers then the bgn radios can deal only with the clients?
the scheme is range extender kind, and in the present setup the wds slave router is using the same channel as the master (as wds client it bonded to the master's channel).

so, how i can set up the ac radios for wds "link" and use different bgn channels for connected devices (for less interference) preferably the "luci" way?
routers flashed with:

oops, i forgot to put in the original message that i am aware the 5gHz link should provide less distance achievable between the 2 routers (extender scheme) but i'am happy to learn the why/why not reasons.

Yes, you can do that (and should, if 5 GHz can do the distance; you can also repeat the 5 GHz signal in addition).

It's the same, create AP(WDS) and STA(WDS) interfaces on the 5 GHz radio. You could set up a new network that doesn't go anywhere just to see how the radios link up and what the signal levels are.

thanx, you mean additionally to present working setup hook up the 5gHz radios wds and should attach them to lan/lan

You can do that, but be sure the Spanning Tree Protocol is enabled on the lan bridge when you have a situation where a network loop could form. Here the links through the LAN on both 2.4 and 5 would be a loop.

I suggested making a separate test network with proto None to hang the radios on to at first. It doesn't actually pass data but lets you see if the radios connect to each other.

I thinks so as i followed atheroswds tutorial on the second router i have the STP enabled (just checked) on the LAN physical page.
should i enable it on the primary router as well?
it looks (i am almost in live) as i enabled SPT on main lan everything collapsed, main router unreachable, slave still ok.
without it (just the slave router SPT on /lan) it was all up.
WDS link on ac channel 36. main bgn ch6 slave bgn ch11.

now i jigi-jigi main router alone.
will revert succeed.

finally i have on both router STP enabled on LAN.
I did not took the 2 far apart to test autoroaming, but i made some tests manually connect each.
R1 = router1ip x.x.x.1 R2=router2 ip x.x.x.2
R1 - ac radio WDS AP - attached LAN - SSID is OpenWrt
R2 - ac radio WDS client - attached LAN
R1 - bgn radio is a common AP with mySSID - attached LAN - free to select channel
R2 - bgn radio also a common AP with mySSID - attached LAN - free to select diff channel
R1 act as DHCP while R2 disabled DHCP

till now it looks any routers bgn AP i connect i have good access to any device in the segment.
i have some home-made esp wifi button they connect well and they find my smart-home switches on the segment (they got reseved address from DHCP).

i will perform some roaming test, in spite smart-home parts will have fixed location, but this whole setup is about web access with roaming in a larger house.

yep, good idea to use 5gHz also as extended.
that will be next step.
fortunately the extended 2.4gHz already works (extended via 5gHz).
i have only usb gsm stick net so first i have to solve that part to have web access on router. (i have 2 usb socket and enough memory to make)