Wonderful, thanks so much for your time and effort, Much appreciated!
@djtenderfoot Thanks a lot for sharing this build. Working flawlessly here. 
It looks like I can't connect to the 5GHz network as a client.
As an access point, the 5 GHz network works well.
And with the network. 2.4 GHz everything is fine: both master and client work well.
Has anyone encountered the same problem?
Are you using a WDS setup? Make sure you lock the BSSID so that it sticks to the 5GHz interface of the main router.
I did initially have that issue and making the Access Points as WDS did the trick for me.
I'm using this router for the second time on vacation and I thought I'd tell about my experiences. (bases on 23.05.3)
It's been working pretty great. My router is set up with these services/features enabled: adblock with adaway/doh list, https dns proxy, upnp (absolutely not needed for my traveling purposes needed but it happened to be enabled nonetheless, so I'm including it here), software offload, travelmate.
I don't know the exact line speed of the internet connection here but on 5gz (on the foreign router which is located in another room - cement walls) my Apple TV get's about 165mbs. My guess it's between 165 and 200mbs.
I'm using this router in client mode to ap repeater with my own subnet. My Apple TV's Speedtest app reports about the same speed on 5ghz client to 5ghz ap. (Which means the single 5hz radio can sustain at least 165mbs up/down at the same time, which is quite remarkable for such a «sh**ty» router)
I can probably load a few more adblock lists, but it WILL oom and reboot if you're careless. In the start I used banip to block public doh but found out adblock has it's own list for that which works fine too.
It will probably benefit from zram if you want to use more lists, but to block the most annoying ads, the adaway list seems to suffice - for that the native 64MB ram seems fine. (I do have a pretty full featured build to make it versatile. I imagine I could save some ram by not including a lot of things)
Hey @djtenderfoot I followed your steps and created a build for dap-1610-a1 with the latest openwrt v23.05.4. Everything works including the 5 GHz radio but WiFi speed is abysmally slow. Any suggestions?
Update: It was a syntax error in dts file, fixed it and now it’s working without any issues.