Hello, 

I have an HDMI and USB-C monitor. I can have them both plugged in and working individually but when both monitors are plugged in only one works at a time. I have tried lowering the resolution on all monitors, updating all drivers using the Lenovo tool and operating system.

Assistance would be appreciated, thank you.

Edit - Another user just reported the same issue on the same exact Lenovo model laptop.

Moderator comment: Moved to the proper forum. (NateS)

Hi mattjelly!

Welcome to community forums

What are the resolution and refresh rates on both monitors?

Just to make sure, are you referring to the Thinkpad T15 Gen 1 20S6? If yes, it can support up to  2 external monitors via HDMI (up to 4096 x 2160 @24Hz), USB-C (up to 4096 x 2304 @60Hz), or Thunderbolt™ (up to 4096 x 2304 @60Hz)

You can refer to this product spreadsheet; https://psref.lenovo.com/Product/ThinkPad/ThinkPad_T15_Gen_1

Jwes_Lenovo

I'm not sure which monitor is plugged in using which cable but I will find out. The monitors appears in the Advanced display settings as - 

Internal monitor is as follows:

Display 1: LG IPS FULLHD
Desktop resolution: 1024 x 768

Active signal resolution: 1920 x 1080

Refresh rate: 50.000Hz

External monitors below:

Display 2: LG IPS FULLHD
Desktop resolution: 1024 x 768

Active signal resolution: 1920 x 1080

Refresh rate: 50.000Hz

Display 2: S24D300

Desktop resolution: 1024 x 768

Active signal resolution: 1920 x 1080

Refresh rate: 50.000Hz

Computer specs below:

For the T15 (type 20S6, 20S7) Laptop (ThinkPad) - Type 20S6 - Model 20S6000XUS, you can try to trace it setting one monitor at a time.

Checking with the user guide here on page 5 shows an option for connecting the two other external monitors
https://download.lenovo.com/pccbbs/mobiles_pdf/t14_t15_p14s_p15s_ug_en.pdf?linkTrack=PSP:ProductInfo:UserGuide

6. USB-C 3.2 Gen 2 / Thunderbolt 3
9. HDMI 1.4b
 
 
 
 
Jwes_Lenovo

page 5 is just 'about this documentation'. Page 12 and beyond describes the connections, saying which ones can support external monitors. But I cannot get more than 1 external monitor to be detected with monitors connected to any of 2 those connections at the same time. It looks like you need the base station to actually have 2 external monitors. A base station is superfluous with remote work but Lenovo needs the $ I guess.