I have a 2017 MacBook Pro. It has 2 USB-C ports on the left side and I use an Aukey hub to provide more ports (4 USB, 1 HDMI, 1 USB-C). I connect one monitor through the hub with the HDMI port and another directly to the MBP with a USB-C adapter. Sometimes I connect with no problem...but more than half the time I have to connect, disconnect, jiggle, jangle, switch ports, reconnect HDMI, etc. and hopefully they will both work. 

Is there any kind of software fix or reset that might solve this issue? Any other thoughts welcome. Thanks.