OK - you don't need a smart connector for the console port to use the CLI for setup...

You probably need to see this:

https://www.cisco.com/c/en/us/support/docs/routers/7000-series-routers/12223-14.html

Forget about the "12-in-1 serial port" that is between the 4 port ethernet switch and the 3G mini-USB port; that one's for serial WAN. The serial port you want is the one with the powder-blue label, the "CON/AUX" port, located below the GE WAN 0 port, with the power input connector to the immediate right.

Get your hands on the RJ-45 Rolled to DB9 console port cable, and plug the RJ45 end into the CON/AUX port on your 819, and the DB9 end into any normal serial port on any PC/MAC (older PC might have the port natively, otherwise USB to DB9 serial cables are dirt cheap).

These links are not an "endorsement"; just a completely typical cable you might use:

https://www.amazon.com/OIKWAN-Rollover-Console-Management-Adapter/dp/B08V539JMQ

https://www.amazon.com/Sabrent-Converter-Prolific-Chipset-CB-DB9P/dp/B00IDSM6BW

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[And for reference, if you are still hung up on using the "other" serial port on this router, I cannot help you! It's the one referenced in this guide: https://www.cisco.com/c/en/us/td/docs/routers/access/800/819/software/configuration/Guide/819_SCG/6ser_conf.html and the cable end looks like this: https://www.amazon.com/EDIMS-Length-Router-CAB-SS-2626X-Serial/dp/B06VXVCM32 And it is *NOT* what you need to use for a CLI/configuration setup... ]