Atheros interface going down automatically

Hi. Inam not an Openwrt power user, but I've been using it for years on a TP-Link AC7 v2.
From the past 2 weeks some issues with it, where its Atheros interface is getting disabled automatically.

My network topology is basically the AC7 configured as my router and DHCP server for the rest of my network. I do have 3 devices connected to the AC7 via cable.
One of these devices is a wifi AP acting simply as a AP, the DHCP server is still the AC7 with openwrt.

From time to time the DHCP server stops working. And today I realized its because the AC7 interfaces are being shut down, for a reason I don't know.

So, openwrt logs a message like:

Atheros AR8216/AR8236/AR8316 ag71xx-mdio.0:00: Port 3 is down

Interestingly enough, when I turn on any system wired connected to the AC7, the Atheros interface comes up again and so, the DHCP server start to reply normally to dhcp requests.

Is there any power saving feature in openwrt, that disables the interfaces after some time? Or maybe somebody has another idea of what can be happening?
My AP is connected all the time to the AC7 btw. So I am not sure why the AP itself doesnt keep the AC7 awake (if, this is a powersaving issue)

Current version running on my AC7:

cat /etc/openwrt_release

DISTRIB_DESCRIPTION='OpenWrt 21.02.1 r16325-88151b8303'

I see the message whenever a wired device is rebooted, shutdown, or turned on.