The below solution was posted -
Change:

activateMonitor: function () {
    if (this.config.turnOffDisplay) {
      // Check if hdmi output is already on
      exec("/opt/vc/bin/tvservice -s").stdout.on("data", function(data) {
        if (data.indexOf("0x120002") !== -1)
          exec("/opt/vc/bin/tvservice --preferred && chvt 6 && chvt 7", null);
      });
    }
  },

  deactivateMonitor: function () {
    if (this.config.turnOffDisplay) {
      exec("/opt/vc/bin/tvservice -o", null);
    }
  },

WIth:

 activateMonitor: function () {
   if (this.config.turnOffDisplay) {
     // Check if hdmi output is already on
     exec("vcgencmd display_power 1").stdout.on("data", function(data) {
       if (data.indexOf("0x120002") !== -1)
         exec("/opt/vc/bin/tvservice --preferred && chvt 6 && chvt 7", null);
     });
   }
 },

 deactivateMonitor: function () {
   if (this.config.turnOffDisplay) {
     exec("vcgencmd display_power 0", null);
   }
 },

However, the node_helper.js language has now changed since the above post to now be:

		if (query.action === "MONITORON")
		{
			exec("tvservice --preferred && sudo chvt 6 && sudo chvt 7", opts, function(error, stdout, stderr){ self.checkForExecError(error, stdout, stderr, res); });
			return true;
		}
		if (query.action === "MONITOROFF")
		{
			exec("tvservice -o", opts, function(error, stdout, stderr){ self.checkForExecError(error, stdout, stderr, res); });
			return true;
		}

I’ve little experience with js coding, and wondered if anyone had already updated the above vcgencmd calls to work with the now current node_helper language? Or if someone could suggest what that language would now be so I don’t break anything ignorantly futzing around?

(Of course, the optimum would be to have a config option officially added to Remote-Control to have the option of using tvservice (as the default), or vcgencmd for those of us that tvservice doesn’t work so well for…)

Many thanks for any help provided.

(Using RPI Zero W / Raspbian Stretch Lite / Dell monitor via HDMI / serveronly mode)