TP-Link TL-WDR4300 (N750) LAN connection not working

I have a freshly installed openwrt 23.05.0 on TP-Link TL-WDR4300. Wifi works fine, but LAN connection does not work. There's no network link on any of the ports.
How can I debug/fix the issue?

Thanks

Did you make configuration changes after installing OpenWrt? Wifi is not enabled by default, so this sounds unusual to say the least.

Originally there was an old openwrt installed on the router. The old version was working but I haven't used for years. I decided to do a fresh start, so I reinstalled the latest version that removed all the configs.
I also read that wifi is not enabled by default, so I was a bit surprised when it worked.
Otherwise it seems that all the configs are lost. There's no password for ssh. I installed luci manually. There was no pass for luci as well and I can't see any non default settings in luci.
The only strange thing that there's no network link on LAN ports, but the router LAN leds are ON.

removed them how ?

I think, installing a full image removed the configs. I installed this image:
https://downloads.openwrt.org/releases/23.05.0/targets/ath79/generic/openwrt-23.05.0-ath79-generic-tplink_tl-wdr4300-v1-squashfs-factory.bin

if you checked the remove config box, yes.
did you ?

hmm I think you installed the wrong version - ending ... -squashfs-factory.bin. This one is used when you have the stock firmware. If you had Openwrt installed then you should have used ....squashfs-sysupgrade.bin

yes, I did

if you used factory, then yes, you did

Can I reinstall again using the same version with ...sysupgrade.bin?

you can try, or flash it from scratch, via TFTP, using the factory image.

I did an upgrade using ...sysupgrade.bin. Now the situation is even worse as there's still no LAN and WIFI also switched off. So I'm not able to reach the router.

try the reset button, or the TFTP factory flash described on the WDR4300 wiki page.