Using TRUNK, on my ZBT-WE826 (MT7620A) neither ethtool nor wii-tool works for eth0, eth0.1 ...
A similar bug for ar... filed in December already.
Is there an alternative to verify settings for the ports ?
Well the best thing is devmem and 7620 datasheet I was doing that with MT7628. BTW some subcommands may still work even if something like ethtool eth0 fails.