External display for macbook air won't detect mac os sierra

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The external monitor does not show up in the 'display' section, and when connected and turned on simply goes to sleep.

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Since the 'update' to High Sierra (which I cannot revert, since it shipped with this OS X), my MacBook Pro 15' (2017) does not recognize my external monitor anymore using the exact same method I used before ( USB-C to DisplayPort adapter). This one shipped with High Sierra, and is now running version 10.13. Eventually, my 2016 model got replaced by a brand-new 2017 model. The MacBook Pro was running Sierra as operating system, and it recognized the external monitor.Īfter I went through a bit of technical problems, however. It was a USB-C to DisplayPort adapter, after which I used a DisplayPort cable to connect it to my external UHD monitor (Philips Brilliance 288P). I purchased an adapter so I could connect it to my external monitor (which functions perfectly). A bit ago I purchased myself a MacBook Pro 15' (2016).