I always run a software firewall on my systems. Although it also provides protection against incoming attacks, its main purpose is to block outgoing access. The only programs that I allow to 'phone home' are those that need the Internet for their basic functions i.e. a browser or email program.
It takes a bit of work configuring it, but after that, all unwanted outgoing accesses from the OS itself are blocked. Other apps are just as easy to block. No telemetry, no automatic updates. Very few problems. YMMV.
Ed
Just wondering what software you use, assuming it's not the router.
I ask because I was under the impression windows firewall is hard coded to allow windows telemetry including updates
I've never heard that windows firewall is hard coded, but it is configured to allow almost all outgoing access by any app, not just telemetry and updates. I'm not that familiar with windows firewall, but I did play with it and I believe that I had it set up to block updates. But it was supposed to give me a popup when an app tried to access the net and I never got that to work. In any case, if you load an external firewall program, windows firewall shuts down. It's likely that any firewall program could be configured to do what you want.
I chose Comodo's Internet Security. You could also use their Firewall program. They're both free, just make sure that you click the correct link. They're similar packages, but have a few different features. Both include the firewall and a module that runs in memory and pops up if a program tries to do something unexpected. You can set different notification levels for this. I normally run 'Paranoid Mode'.
https://www.comodo.com/home/internet-security/free-internet-security.php?af=3272https://www.comodo.com/home/internet-security/firewall.phpOne thing I like to see is that after I boot up, the network icon in the system tray says that as far as Windows is concerned, I'm not connected to the net! That doesn't change unless and until I use a program like Firefox or Thunderbird. Then Windows realizes that I am connected and updates the icon.
Ed