My computer is DELL inspiron 5000, model 5579 with cpu intel i7-855u, graphic 620.
When loaded windows 10, my computer can display 2560x1440 resolution in external monitor, but when loaded ubuntu 18.04 and connect to the same monitor, it can only display 1920x1080.
Can I display 2560x1440 in external monitor when loaded in ubuntu.
That would be an ubuntu driver issue. From where do you get the ubuntu driver?
From the graphics support page:
https://www.intel.com/content/www/us/en/support/articles/000005526/graphics-drivers.html Supported Operating Systems for Intel® Graphics Products
"Intel does not provide direct downloads and technical support for Linux drivers. The Intel Graphics Linux driver is primarily supported through the original equipment manufacturer (OEM), the Linux distribution vendor, or by the Intel Open Source Technology Center at 01.org/linuxgraphics. For more information, see the Drivers for Linux document for more details."