What opensource task manager would you recommend?

Question

Task Management

Hello. If you have used task managers in your practice, what would you advise?

I only contacted RedMine, and it didn’t really work for me, since it’s a rather wooden interface. Also, it's written in Ruby, which I don't know.

I would like something PHP-shnoe with clients on iOS and Android, and not cloudy. The scheduler should run exactly on our server - this is the will of the boss, and this is not discussed.

I googled on the Internet, googled from an interesting trello with a nice interface, and Microsoft's scheduler, but it turned out that Microsoft's scheduler only works from Windows, and Trello is an online cloud one. In addition, the search results are full of garbage results with discussions about crontab, so I could not google "Opensource task scheduler" qualitatively.

Therefore, I turn to you - maybe someone has experience and advice. Please share.

From the functionality, roles are needed (rights - you can / cannot change the artist, etc.), the title of the task, the description of the task, and the ability to comment on it with attaching files or screenshots, setting a deadline, and calculating the time spent.

It would be cool if there were notifications in some messenger, or a client for iOS and Android, although Android is not necessary.

Yes, very little functionality is required. So far, I don’t feel like writing myself, I want to first feel the ready-made options, maybe everything will suit me.

I will be grateful for advice.