The firmware update might revive it, but it depends on your computer and it's age and system. My laptop is now 6 years old, but still doing fine.
Cisco and Motorola are (2) great product names, as Joelsanders said, stay with a Docsis 3, just look on the outside of any product box to see if that's what the product is.
As far as securtiy of a router, yes and no to answer your question. If someone really wants to hack into your system, if they are good, then they will. Always stay current with any Microsoft updates and patches, and anti-virus and malware software.