I am having weird issues with my early 2013 Macbook Pro, High Sierra 10.13
This has happened before and resolved spontaneously.
Basically, I unplugged my macbook and used it without an external monitor for several days, sometimes putting it to sleep. Today, I tried to connect to my monitor (HDMI) and it detects it, but no pictures comes up and the monitor (Acer) says No signal. It then proceeds to continue switching resolutions as if trying to repeatedly connect. The monitor is functional (used another computer) but some setting on my macbook is preventing it from connecting. A VGA to DP also does not resolve the issue.
I have tried restarting, resetting SMB and NVram multiple times, switched cables, and am at my wits end. Any thoughts?