my dell u3818dw just arrived today. unpacked it - looked great.
plugged it in to my macbook pro retina mid 2014. looked fantastic. lots off programs. reset resolution from scaled to native for monitor. everything worked great.
powered it off. unplugged the minidisplayport cable from the laptop and the power cord from the outlet and routed the cables behind my desk and plugged them back in. screen now says "no dp signal from your device." i did not change anything other than to unplug the cable and power cord and plug them back in.
disconnected and reconnected minidisplayport cable several times each from the laptop and from the monitor. powered both monitor and laptop off and back on several times. reset the input from auto to displayport and back. turned hdmi 1.2 off and back on.
one odd thing is that when i unplug the minidisplayport cable from the laptop and plug it back in, the monitor briefly says, "scanning for signal" as if it knows a cable was just plugged in to my computer; but then it says no dp signal from your device.
there are some web posts about this error message on older dell monitors that say to plug an hdmi cable, but that won't work for me as my macbook pro only has minidisplayport out.
anyone know how to fix this? i was loving the monitor so much for the 15 minutes it was working! i would hate to return it.
First, as you can see in the image below taken directly from the monitor page, the Apple proprietary hardware, operating system (including Windows Bootcamp), cabling, and drivers were not tested/validated by Dell. Since we at Dell are not trained in the usage of the Apple hardware and operating system, you should also ask the Apple users on the Apple Forum for troubleshooting and cabling opinions.
All that being said...
You state, "disconnected and reconnected minidisplayport cable several times each from the laptop and from the monitor"
The U3818DW only shipped with the following video cables =
DP to DP
HDMI to HDMI
USB Type-C to USB Type-C
If you are connecting to the U3818DW DP in port, then you must be using some 3rd party Thunderbolt 2/mDP to DP cable? You cannot have both that cable and the HDMI to HDMI cable connected to the U3818DW and the MacBook at the same time.
* Turn the MacBook and the U3818DW off
* Disconnect every cable from the U3818DW (including the power cable)
* Press and hold in the U3818DW power button for 10 seconds
* Reconnect the power cable to the U3818DW
* Open the MacBook lid
* Turn the MacBook on
* Connect in this way =
MacBook Thunderbolt 2/mDP out port --> 3rd party mDP to DP cable --> U3818DW DP in port
* Turn the U3818DW on
* Press the U3818DW Menu button
* Go to Input Source
* Check DP
* Exit the Menu
* Go to the Apple operating system and tell it to extend to the U3818DW (just guessing there)