Something that's nice about Let's Encrypt is that it forces you to change something every few months. After the first couple months, you'll probably get your issues worked out. If you just change certs every few years, then every few years you have some sort of disaster because of the "well we fixed it, we don't have to worry for two years" effect. A broader lesson is the importance of "trying out" rare events, even…
Although, speaking of Let's Encrypt, there will be a series of disruptive events over the next 18 months or so. * Soon (although when exactly I'm not sure because it has been delayed at least once) the Let's Encrypt systems will tell compliant ACME clients that the "correct" intermediate is Let's Encrypt's ISRG-signed X3 intermediate. This is a different certificate for the same X3 private key you're used to but not…
> Six year old Android phones, the Windows XP system you know should have been retired, a VoIP desk phone running out-of-date firmware, stuff like that.
If these can’t connect that is a feature, not a bug.