I use free certificates from Let's Encrypt. The process of refreshing the certs is a bit annoying because I need to shut down stunnel and fire up nginx to create the certs then revert back to stunnel when I am done. Otherwise, no problems at all. If you want instructions for Let's Encrypt, I can post them.
Here is my stunnel config
Code:
output = C:\Program Files\stunnel\config\stunnel.log
[Blue-Iris]
accept = 443
connect = 81
CApath = C:\Program Files\stunnel\config\
cert = C:\Program Files\stunnel\config\certX.crt.pem
key = C:\Program Files\stunnel\config\certX.key.pem
;CAfile = C:\Program Files\stunnel\config\certX-issuer.crt.pem