External monitor connected to Macbook pro Retina flickers, how to solve this problem?

Question

Monitors

Connected external monitor to macbook pro retina 13 2015 with HDMI cable.
At default settings, the monitor flickers constantly.
If you hold Alt and select not a specific resolution, but 1080p, then everything is fine, but the panel with the menu and the rest goes beyond the monitor.
Help, what will help solve the problem?
Thanks in advance.

Answer 1

the same problem)
I have a monitor with a resolution https://catalog.onliner.by/display/lg/29um58p
This is due to a non-standard resolution
There is also a freeze menu or animation - I'm already thinking of buying a regular fullHD monitor)

Answer 2

sometimes it happens that the cable is too long or bent in some places, try to replace the cable. The longer it is, the worse the signal.

Answer 3

If someone got here from Google in the same way as I did, then here is the solution that helped me - reset SMC
https://support.apple.com/en-us/HT201295