Sorry for this late reply.
I tried hours and hours, and then days to connect to serial line on all of my switches (bought on purpose).
Unfortunately, I don't have the required SPI bus analysis tools to connect to the Switch. Any help appreciated.
Supporting a vast range of switches would be the last frontier for OpenWRT. This is silly to think that all those switches are Open Source and we can't connect to the serial console.
I posted a question on D-Link support website:
(Last edited by gnutella on 25 Jul 2017, 08:55)