# No Signal with USB-C Monitor on HB31C3A1CDPPD3 and DP-Alt handset **URL:** \ **Category:** Docks, Hubs, Display Adapters\ **Tags:** usbc\ **Created:** [September 19, 2026, 4:30pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988 "2026-09-19T16:30:28Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![FPDesktop32](https://avatars.discourse-cdn.com/v4/letter/f/e36b37/32.png) [@FPDesktop32](https://community.startech.com/u/FPDesktop32)\ **Post date:** [September 19, 2026, 4:30pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/1 "2026-09-19T16:30:28Z")
Dear StarTech experts, connecting a _FP5_ handset with DP-Alt support to [HB31C3A1CDPPD3](https://www.startech.com/en-eu/usb-hubs/hb31c3a1cdppd3) (_HB31_) and from there by USB-C cable to a _3K USB-C monitor_ gives here a “ **No Signal** ” on the screen. However both, the monitor and the _HB31_ are powered by 80W and 100W (which is overkill, as the _HB31_ supports already PD). As the [HB31C3A1CDPPD3](https://www.startech.com/en-eu/usb-hubs/hb31c3a1cdppd3) features a _VIA - VL103_ chip, I assumed it can handle a monitor over USB-C. Connecting the USB-C cable directly between handset and USB-C monitor works fine. My goal is to connect the handset (USB-C) by cable to ethernet (RJ45), mouse (USB-A), keyboard (USB-A) and monitor (USB-C). Is there a reason, it not to operate, as I expected it to work? ---
**Author:** ![EmmanuelB](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/emmanuelb/32/24_2.png) [@EmmanuelB](https://community.startech.com/u/EmmanuelB)\ **Post date:** [September 21, 2026, 2:04pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/3 "2026-09-21T14:04:13Z")
Hello @FPDesktop32 and thank you for your interest in our Community. I would like to confirm that your expectation does indeed mostly match this device (although it has no RJ45 ports, so I assume you are using a USB Network adapter). Since the monitor works when connected directly to the Fairphone 5, the phone is clearly capable of producing a DP Alt Mode signal. The next step would therefore be to determine whether this is a hardware issue with the hub/cabling or a USB-C/DP Alt Mode interoperability issue with the Fairphone. A few things I would recommend trying: - Make sure the monitor is connected to the **VIDEO OUT** USB-C port and not the separate 100W PD-only input on the other side. - Use the same USB-C cable between the hub and monitor that works when the monitor is connected directly to the phone. - Connect the hub’s power adapter (if you are using any) and monitor first, then connect the hub to the Fairphone. - Try restarting the Fairphone while the powered hub and monitor are already connected. - Make sure the Fairphone 5 is running the latest available software (there are known DP Alt Mode issues fixed by the Fairphone’s August software update). - **Important** (if possible) → test the **[HB31C3A1CDPPD3](https://www.startech.com/HB31C3A1CDPPD3)** and USB-C monitor with another USB-C video source (laptop/computer etc.) that supports DP Alt Mode. If the monitor works through the **[HB31C3A1CDPPD3](https://www.startech.com/HB31C3A1CDPPD3)** with another DP Alt Mode host, that would strongly suggest that the hub itself is operating normally and that the issue is related to USB-C/DisplayPort negotiation with the Fairphone 5. It would also be useful to know whether the **Ethernet, keyboard and mouse are detected by the Fairphone through the hub while the monitor shows “No Signal.”** That would help us determine whether only the DisplayPort Alt Mode negotiation is failing or whether the entire USB-C connection is affected. We look forward to hearing back from you! Emmanuel B. [StarTech.com](http://StarTech.com) Support ---
**Author:** ![FPDesktop32](https://avatars.discourse-cdn.com/v4/letter/f/e36b37/32.png) [@FPDesktop32](https://community.startech.com/u/FPDesktop32)\ **Post date:** [September 21, 2026, 2:26pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/4 "2026-09-21T14:26:55Z")
Sorry for the confusion. The adapter is called 10G2A1C25EPD. > **[Enable 2.5G ethernet, 100W PD pass-through, and add three USB 3.2 10Gbps...](https://www.startech.com/en-us/usb-hubs/10g2a1c25epd-usb-hub)** > > 3-Port USB-C Hub with 2.5 Gbps Ethernet and 100W Power Delivery Pass-Through Port, USB 3.2 10Gbps, 2x USB-A/1x USB-C, Portable USB Type-C Adapter Hub Thanks for your precise reply. The bought adapter has already a RJ45 port and the mentioned _VIA - VL103_ chip. The Fairphone5 uses keybord, mouse and cable internet just fine, while the No Signal is shown on the 3K HDR display. Should I adapt the title line to the correct adapter? ---
**Author:** ![EmmanuelB](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/emmanuelb/32/24_2.png) [@EmmanuelB](https://community.startech.com/u/EmmanuelB)\ **Post date:** [September 21, 2026, 4:10pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/5 "2026-09-21T16:10:03Z")
Hello @FPDesktop32 , This does confirm the issue then: our **[10G2A1C25EPD-USB-HUB](https://www.startech.com/10G2A1C25EPD-USB-HUB)** is a USB-C data hub only and does not support DP Alt Mode. The only travel docks (not full size docks) we offer with **USB-C** DP Alt Mode video support output would be the following: - **[HB31C3A1CDPPD3](https://www.startech.com/HB31C3A1CDPPD3)** _(no Ethernet port)_ - **[DKM31C3HVCPD](https://www.startech.com/DKM31C3HVCPD)** _(Discontinued, few left in stock)_ - **[174B-USB4-MULTIPORT](https://www.startech.com/174B-USB4-MULTIPORT)** - **[318B-USB4MULTIPORT](https://www.startech.com/318B-USB4MULTIPORT)** _(Coming soon)_ I hope this helps better understand the situation and available solutions. Please let me know if you have any further questions and have an excellent day! Emmanuel B. [StarTech.com](http://StarTech.com) Support ---
**Author:** ![system](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/system/32/2_2.png) [@system](https://community.startech.com/u/system)\ **Post date:** [September 22, 2026, 8:48am UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/6 "2026-09-22T08:48:15Z")
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**Author:** ![FPDesktop32](https://avatars.discourse-cdn.com/v4/letter/f/e36b37/32.png) [@FPDesktop32](https://community.startech.com/u/FPDesktop32)\ **Post date:** [September 22, 2026, 8:48am UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/7 "2026-09-22T08:48:36Z")
Thanks for the display adapter list and your spot on support. The **DKM31C3HVCPD** looks fine for what I asked. ---
**Author:** ![system](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/system/32/2_2.png) [@system](https://community.startech.com/u/system)\ **Post date:** [September 25, 2026, 12:27pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/8 "2026-09-25T12:27:03Z")
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**Author:** ![FPDesktop32](https://avatars.discourse-cdn.com/v4/letter/f/e36b37/32.png) [@FPDesktop32](https://community.startech.com/u/FPDesktop32)\ **Post date:** [October 6, 2026, 11:38am UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/9 "2026-10-06T11:38:21Z")
The **DKM31C3HVCPD** adapter arrived is tested and works fantastic. Thanks for your support. ---
**Author:** ![EmmanuelB](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/emmanuelb/32/24_2.png) [@EmmanuelB](https://community.startech.com/u/EmmanuelB)\ **Post date:** [October 6, 2026, 12:02pm UTC](https://community.startech.com/t/no-signal-with-usb-c-monitor-on-hb31c3a1cdppd3-and-dp-alt-handset/1988/10 "2026-10-06T12:02:46Z")
Glad you got a working solution. Let us know if you need anything and have a great day! Emmanuel B. [StarTech.com](http://StarTech.com) Support