After a switch by Debian project to a wayland protocol, I am not able to use a full resolution of our monitors.
Monitors are LG-29UM57-P. Their default and native resolution is 2560x1080.

Monitor is connected to PC via DisplayPort interface.

This issue only manifested after migrating from GNU/Debian v8 Jessie to GNU/Debian v 9 Stretch and to GNU/Debian v10 Buster.

Monitor functioned as expected under Debian 8 Jessie at it's full 2560x1080 resolution.
There was no change in hardware what so ever. Once Debian Stretch was installed, it is no longer possible to set a monitor resolution to it's native resolution.

Same issue with Debian 10 Buster.

Please advise what can be done (other than rolling back to Debian Jessie) to switch XServer+Wayland to a proper full resolution.

Please note, exact same hardware PC/Graphical card + displayport cable + Monitor worked as expected with Debian Jessie, therefor this is not a hardware limitation.

Thank you for looking in to this matter.

HW details:
System:    Host: t420 Kernel: 4.19.0-6-amd64 x86_64 bits: 64 Desktop: Gnome 3.30.2 Distro: Debian GNU/Linux 10 (buster)
Machine:   Type: Laptop System: LENOVO product: 4178C9U v: ThinkPad T420
CPU:       Topology: Dual Core model: Intel Core i7-2640M bits: 64 type: MT MCP L2 cache: 4096 KiB
           Speed: 798 MHz min/max: 800/3500 MHz Core speeds (MHz): 1: 798 2: 797 3: 797 4: 797
Graphics:  Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics driver: i915 v: kernel
           Display: wayland server: X.Org 1.20.4 driver: i915 resolution: 1600x900~60Hz, 1920x1080~60Hz
           OpenGL: renderer: Mesa DRI Intel Sandybridge Mobile v: 3.3 Mesa 18.3.6


Damien