Martin Boller 
#Cisco #IOS #TLS #SelfSigned #Expired #YouAreShitOutOfLuck 😪
Try this
nmap --script=ssl-cert.nse 10.10.10.0/24 | grep -i Issuer | grep -i 'IOS-Self-Signed-Certificate'
If the above returns any results (adjust subnets accordingly) then you might want to read this:
https://www.cisco.com/c/en/us/support/docs/field-notices/704/fn70489.html
Field Notice: FN - 70489 - PKI Self-Signed Certificate Expiration in Cisco IOS and Cisco IOS XE Software - Software Upgrade Recommended
Self-signed X.509 PKI certificates (SSC) that were generated on devices that run affected Cisco IOS or Cisco IOS XE software releases expire on 2020-01-01 00:00:00 UTC. New self-signed certificates cannot be created on affected devices after 2020-01-01 00:00:00 UTC. Any service that relies on these self-signed certificates to establish or terminate a secure connection might not work after the certificate expires.