Is It A Boundary Matter?

My mother lives thousands of miles away from me and we talk once a week on the phone. On this long distance call she always chooses to tell me of all the negative stuff that happened the past week, nothing seems to be right, no one behaves as they should, and no one is supposed to do what they should be doing.
She curses and is full of negativity and I see that it causes me not to look forward to our calls because she is so negative.
When I tried ‘coaching’ her to see the positive in everything, she argues back and tries to prove me wrong.

So, since coaching her doesn’t work, I was wondering if it makes sense to set a boundary with her and tell her I am not willing to hear all this negative stuff and if she talks again this way, we will have to hang up.
It sounds mean to do since I am aware she will not change and she is waiting for our call every week. She sees that as an opportunity to vent out.
The other option is to let her be who she is, not set any conditions and not try to coach her to positive thinking, and do work to heal myself after each call and brush off the negativity from me.
What are your thoughts on that?