As I said, the workaround worked. To help others looking for a solution and finding this bug, I will show it here for my configuration:
1.) Open a terminal 2.) Call xrandr to see, how your desired device is called. In my case, it's called "HDMI-1". If you have more than one, you may guess, but output should by clear enough. 3.) Call cvt with desired resolution and frequency. In my case it must be 2560x1080 with 30 (Hz), If you are unsure you have to try (I tried 60 Hz first - didn't work in the last step no. 6): cvt 2560 1080 30 Output in my case is # 2560x1080 29.97 Hz (CVT) hsync: 33.03 kHz; pclk: 106.75 MHz Modeline "2560x1080_30.00" 106.75 2560 2640 2896 3232 1080 1083 1093 1102 -hsync +vsync 4.) Call xrandr to set new mode, copy everything after "Modeline": xrandr --newmode "2560x1080_30.00" 106.75 2560 2640 2896 3232 1080 1083 1093 1102 -hsync +vsync (The name in quotation marks could be changed, but no need to do so.) 5.) Call xrandr to add this mode by it's name to your desired device: xrandr --addmode HDMI-1 2560x1080_30.00 6.) Call xrandr to set your desired device (here. HDMI-1) to the mode xrandr --output HDMI-1 --mode 2560x1080_30.00 Instead of step 6 via terminal you could use the GUI to change the resolution, it should be there now. Hope this may help somebody. It is not persistent. I made a script and added it to autostart. There may be other ways, maybe a config file for xrandr? -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1929456 Title: XrandR does not propose 21:9 resolution Status in xorg package in Ubuntu: New Bug description: If come here over bug 1895301 "XrandR does not propose 3440x1440 21:9 resolution". In bug 1895301 sombody wrote "We just need one person experiencing the bug to open a bug with the relevant system details automatically attached." - so I did. I have a similar problem with a 21:9 monitor with a resolution of 2560x1080. It's a LG 25UB55-B on a HP docking station A7E32A, DVI output with adapter to HDMI, HDMI cable and input to the monitor via HDMI. Laptop is an HP Elitebook 8440p (Intel i5-520 with Intel HD Graphics (ILK)), internal display with 1366*768 is in use as well. I had Ubuntu 18.04 LTS before until January this year, with automatic updates on, so presumably up to date. There it worked fine out of the box, i.e. since first install I had the full resolution of 21:9 in 2560x1080 on my external monitor. I didn't change any hardware, just installed Ubuntu 20.04 from DVD, an it stopped working. I got only 16:9 with 1920x1080. I've updated to Ubuntu 20.10, tried Ubuntu 21.04 (from DVD as well), changed cable and adapter, nothing helped. Did some reseach with google and found the mentioned bug 1895301. The workaround worked, I got full resolution of 2560x1080 on the external display. It is not permanent, so at the moment of filing this bug, I'm still back on the 16:9 with 1920x1080. ProblemType: Bug DistroRelease: Ubuntu 20.10 Package: xorg 1:7.7+19ubuntu15 ProcVersionSignature: Ubuntu 5.8.0-53.60-generic 5.8.18 Uname: Linux 5.8.0-53-generic x86_64 ApportVersion: 2.20.11-0ubuntu50.6 Architecture: amd64 BootLog: Error: [Errno 13] Keine Berechtigung: '/var/log/boot.log' CasperMD5CheckResult: skip CompositorRunning: None CurrentDesktop: ubuntu:GNOME CurrentDmesg: Error: command ['pkexec', 'dmesg'] failed with exit code 126: Error executing command as another user: Request dismissed Date: Mon May 24 20:23:52 2021 DistUpgraded: 2021-05-23 15:18:23,444 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Kindprozess »./xorg_fix_proprietary.py« konnte nicht ausgeführt werden (Datei oder Verzeichnis nicht gefunden) (8)) DistroCodename: groovy DistroVariant: ubuntu ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 02) (prog-if 00 [VGA controller]) Subsystem: Hewlett-Packard Company Core Processor Integrated Graphics Controller [103c:172a] InstallationDate: Installed on 2021-02-10 (103 days ago) InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731) MachineType: Hewlett-Packard HP EliteBook 8440p ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=de_DE.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.8.0-53-generic root=/dev/mapper/vgubuntu-root ro quiet splash vt.handoff=7 SourcePackage: xorg UpgradeStatus: Upgraded to groovy on 2021-05-23 (1 days ago) dmi.bios.date: 09/13/2013 dmi.bios.release: 15.36 dmi.bios.vendor: Hewlett-Packard dmi.bios.version: 68CCU Ver. F.24 dmi.board.name: 172A dmi.board.vendor: Hewlett-Packard dmi.board.version: KBC Version 30.34 dmi.chassis.asset.tag: CZC040C94D dmi.chassis.type: 10 dmi.chassis.vendor: Hewlett-Packard dmi.ec.firmware.release: 48.52 dmi.modalias: dmi:bvnHewlett-Packard:bvr68CCUVer.F.24:bd09/13/2013:br15.36:efr48.52:svnHewlett-Packard:pnHPEliteBook8440p:pvr:rvnHewlett-Packard:rn172A:rvrKBCVersion30.34:cvnHewlett-Packard:ct10:cvr: dmi.product.family: 103C_5336AN dmi.product.name: HP EliteBook 8440p dmi.product.sku: J2544631 dmi.sys.vendor: Hewlett-Packard version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.102-1ubuntu1 version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.6-0ubuntu0.20.10.1 version.libgl1-mesa-glx: libgl1-mesa-glx N/A version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1.3 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1ubuntu1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200714-1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1929456/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp