[AR150] installing vanilla openWrt, a doubt

I would install a clean vanilla edition of openWrt on this router.
OpenWrt related wiki page says to just upgrade the linked firmware from the web menù. I did it once but something goes wrong (maybe the default firmware, 2.something, was too old?) so I installed lastest custom firmware via Uboot (it is great, good job). I’ve seen that there a clean version on the download area of gl inet site for this minirouter firmware, but it seems old, file is tagged “2018”.
Now, to avoid problem, do you think I can retry to upload again the vanilla firmware? If it goes ok, I have to connect to instead of the custom firmware ip LAN or WAN?
Thanks for any advice!

You can just load Vanilla openwrt. Try latest openwrt 21.02

After you flash the firmware, go to to access the UI. You should connect the the LAN.

uhm, some direct link for the right 21.02 sysupgrade.bin?
by the way, I do not need last openwrt (it is in rc4…), last stable may be ok for me.
So I should connect both WAN (for poe) and LAN? Maybe I have to connect both WAN (with main router) and LAN (with my pc, directly) for config, than using only WAN. In this case I just have to add a firewall rule to allow incoming traffic from my lan devices to ar150 WAN, tcp/udp port 80.

Try openwrt firmware selector