While we do use some of those methods, sadly, we are not in possession of much of the hardware that our software runs. Making it impossible for us to fully test

While we do use some of those methods, sadly, we are not in possession of much of the hardware that our software runs. Making it impossible for us to fully test ourselves; we can usually bank on a period of testing on a customer site during installation, but after that, we're out of luck. Often the hardware claims to support some protocol, but we've found that really, that means "a variation on the theme of a given protocol" so ensuring that we still meet the protocol isn't quite a guarantee of success. Customers are often sympathetic to the idea that their hardware doesn't quite work as advertised - but not very sympathetic. There is often literally no way for us to know that we've broken it until a customer upgrades and discovers it no longer runs their hardware as it used to. Which does happen.