Wherever it makes sense for you and your organisation. There's not a list of approved "boring technology" and unapproved "exciting but scary technology". It's not about the age of the technology, but your level of experience with it. If you know it inside out, understand its failure modes and can easily find information when something goes wrong it's "boring".
If your team can configure AWS services in their sleep but have never touched a bare metal box then AWS is boring. On the flip side, if you're a bunch of Linux greybeards and wrote the book on iptables but can barely spell VPC then on-prem is boring.
This is also where the concept of "innovation tokens" comes in. C++ is well established and quite far from innovative on its own, but if you're building a web app and your team is full of new graduates and interns that have only ever touched Javascript and Python then using C++ would spend one of your "innovation tokens" as your team is busy learning it instead of learning the business domain.