Which firmware should I choose for Buffalo WZR-HP-G300NH?

There are 2 firmwares for Buffalo WZR-HP-G300NH v1

Buffalo WZR-HP-G300NH (RTL8366RB switch)

Buffalo WZR-HP-G300NH (RTL8366S switch)

There's no such problem before, but 20.x

See https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=bc356de2850f14629cb1301be719772fa1212e72

ath79: Add support for Buffalo WZR-HP-G300NH

This device is a wireless router working on 2.4GHz band based on
Qualcom/Atheros AR9132 rev 2 SoC and is accompanied by Atheros AR9103
wireless chip and Realtek RTL8366RB/S switches. Due to two different
switches being used also two different devices are provided.
Flash instruction:

  • NOTE: Pay attention to the switch variant and choose the image to
    flash accordingly. (dmesg / kernel logs can tell it)

How do I know which switch my router use?

"(dmesg / kernel logs can tell it)" How to operate?

""(dmesg / kernel logs can tell it)" How to operate?"

Log in via ssh, and run "dmesg | grep 8366" (without quotes)

Alternatively, for me, when I log in to the luci web interface on 19.07, and navigate to Network -> Switch, it apparently shows me which variant of switch is in use... "Switch "switch0" (RTL8366S)"