My laptop runs an external monitor at 4K, 60 Hz through a direct USB-C-to-DisplayPort cable. Through a USB-C hub’s HDMI output, the same monitor only offers 30 Hz at 4K. At 1080p, 60 Hz is available.
The hub also connects an external SSD and Ethernet. Its product page says “4K HDMI,” but doesn’t specify a refresh rate.
Before replacing anything, how can I tell whether the limit comes from the hub’s HDMI hardware, its use of DisplayPort Alt Mode bandwidth, or the HDMI cable? Would disconnecting the USB devices be a meaningful test, or can the hub reserve bandwidth regardless of whether those devices are active?
I’d appreciate a short checklist of specifications to verify on the laptop, hub, and cable. I don’t want to buy another hub based on a “4K” label and end up with the same restriction.
