My Galaxy S25 Ultra has a severe HDMI connectivity problem with my Acer monitor when using DeX. The connection repeatedly disconnects for 5-10 minutes before stabilizing, happening every time I connect.
I've tried restarting and updating my phone. Is this a known DeX issue with the S25 Ultra, a phone hardware problem, or an incompatibility with my monitor or adapter?
Details:
Phone: Galaxy S25 Ultra
Monitor: Acer monitor ([Your Acer Monitor Model, if you know it])
Adapter: USB-C to HDMI ([Your Adapter Brand/Model, if known])
Please help me diagnose and resolve this. DeX is crucial for my work.
My phone won't spit out anything over HDMI. I get an "external display connected" notification at the bottom of the screen, but then nothing. No Dex, no mirroring. I've tried two different adapters and two different cables. Absolutely nothing.
Same problems with HDMI connectivity stability, multiple tested good (with Note 20 Ultra 5G) USB-C > HDMI / USB, etc adapters, multiple known good (with Note 20 Ultra 5G) monitors/displays. It appears the Samsung Galaxy S25 Ultra 5G is providing less current (not voltage) to the USB-C port. One partial workaround is to connect the USB-C > HDMI or USB-C > multi-plug adapter to a USB charger/power bank to supplement additional current to drive the HDMI port. This is still not as reliable as the Note 20 Ultra 5G (rock solid), but if the USB-C connector is not touched at all, the display remains mostly stable.
