Yes, it may seem a bit ironic in that they are generally known best for spying on their own citizens and others, and you may be forgiven for thinking this is some ploy to embed malware into your router by them, but no, it is all very practical and solid advice written in easy to read language.
Of course, you’ll visit their website using a VPN connection
See https://www.nsa.gov/Press-Room/Cybersecurity-Advisories-Guidance/