Is it for IP/Lan communication or is it Serial/RS232 over RJ45? If it's for IP/Lan, the high speed signal and noise rejection/specification relies on the twisted pairs. So I would not try running LAN/IP network over 9pin serial. Depending on distance it might work (like if it's short), but seems like a bad idea to me. If this is just normal serial RS232 that uses RJ45 as a connection type, that should work fine. More on reddit.com

You don't need to do anything special on the patch/extension side. Any RJ45 coupler/patch will result in no wire transposition. Only one cable in the chain needs to be a rollover, the rest can be Ethernet-spec. So: ACS - Rollover - Anything - Switch This is similar to how you can extend your laptop rollover cable with a standard female-female coupler and patch cable. Get some flat, 8-wire cable to make your rollover cables if you want to make your life easy and ditch anything DB9 unless necessary. I know this from direct experience. We use Avocent everywhere. Feel free to ask if you have more questions. More on reddit.com

If you are so inclined then you can make a cable up with pins 2,3 and 7 connected, that will often work and the pins are the same until you get to >25. If it doesn't then swap pins 2 and 3 at one end and try again. If not then there are a million possible issues. More on reddit.com

As near as I can tell, RJ45 console ports on Mikrotik devices use the same pinning as Cisco console ports - so a standard Cisco console adapter or cable should work. You are talking about a *console* port right? Not an Ethernet port? edit: Wait. What? The RB1100 has a DB9 already. You don't need an adapter. You would connect it to a serial port on a PC and use a terminal program to access it. If you don't hjave a PC with a serial port, you could plug a USB serial port adapter into a USB port on your PC. Something like this: https://www.amazon.com/axGear-RS232-Serial-Adapter-Satellite/dp/B019GQNYPQ More on reddit.com