Probably like many, I've got a stack of these DIY DB-9 to RJ-45 adapters for console access because every manufacturer is special and needs their own unique pinout to accomplish basic serial communication.... Worked well enough with my Toughbook CF-19, but need another serial extension cable to fit in the flush DB-9 ports on things like my Dell Latitude Rugged laptop and CF-20 tablet.
Cleaning/reorganizing my tool bag today, looking at these things, and curious if there's a better mousetrap out there? I know could just pick up a generic premolded RJ45 female to DB-9 adapter, then make custom CAT5 cables to match, but that would take up a lot more room in the tool bag too.
Would be great if someone made something similar to these custom adapters but with a molded DB-9 end, or maybe something like a RJ-45 coupler that could be repinned, so I wouldn't have to carry a bunch of bulky cables.
Compatible USB to RJ45 Serial Rollover Cable for RB3011
USB-C to RJ45 serial rollover adapter F/M
IO Link kind of sucks
Better DB-9 to RJ-45 solutions?
Videos
No. Ethernet ports can't transmit or receive RS-232 signals.
If your laptop has a traditional DB9 RS-232 serial port, use that with the appropriate serial cable. If it doesn't, use a USB to RS-232 serial adapter.
If you have something like this item, then it is merely a pinout adapter and not a serial/ethernet device.

You could use one of these on each end of a RJ45 cable to make a serial cable. That serial cable could run through structured cable installed inside a wall or similar, but it cannot run through an ethernet switch or vlan.