Which OpenSource project management system to choose?

Question

CRM

Hello.
I am looking for an open source project management system.
The functionality is minimal:

• Projects
  
• Tasks
  
• notes
  
• Comments on tasks (and possibly projects)
  
• Calendar
  

if possible:

• integration with mail services
  
• telegram integration
  

Even if the system is minimally paid, it will do, the main condition is that the system must be installed on a separate server.
Can be who faced? From the found: CRM manager (yes, such a strange name), but I did not find a calendar there.

Answer 1

https://www.onlyoffice.com/ru/ one of the most loyal systems to the developer and user, very wide functionality, it is possible to brand under your own brand or the customer's brand, there is a mobile platform with a lot of functionality

Answer 2

https://taiga.io/