What is Reddit's opinion of StarTech.com 4 Port USB to Serial RS232 Adapter - Wall Mount - Din Rail - COM Port Retention - FTDI USB to DB9 RS232 Hub (ICUSB2324I)?
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By popularity on Reddit, this product is:

#4850 in Computer Cables & Interconnects

are you wanting rollover cables or just ip based oobm?

for rollover cables i have used a https://www.amazon.com/dp/B008U3OVHW/ref=twister_B00LCRFHRQ?_encoding=UTF8&psc=1 attached to an intel nuc with bombgar on it to access it.

for network based you can get an intel nuc with multiple nics and usb nics.

costs a bit more than a pi but can be used for other stuff like local logging ect.

< $50

< $50

< $50