I have a subscription Trial for testing Nethsecurity,
but DPI telegram filter doesn`t works,
Welcome Bob and thanks for testing NethSecurity.
Sorry for the delayed response, but I was on vacation 
The DPI feature for subscription was still not available, but it has passed the testing just today: DPI signatures for community subscriptions · Issue #603 · NethServer/nethsecurity · GitHub
We hope to release it next week.