Thanks for the log. There doesn't seem to be anything relevant there, at least not for the past few days. So it seems like the kernel isn't aware of the problem.
Indeed this looks like a bad cable or bad connection somewhere. Especially if fullscreening a window triggered the problem -- that suggests there's a bandwidth limit being exceeded, caused by a hardware problem. Most likely the cable or one of its connections, but there's a slim chance the monitor itself or even the laptop is faulty and unable to maintain a stable link at 4K 60Hz. P.S. The monitor is not "a very popular Samsung one". It appears to be an Acer B326HK. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1929209 Title: external monitor goes black for several seconds at a time, randomly Status in linux package in Ubuntu: Incomplete Bug description: At times it is completely debilitating; at other times it does not happen for hours. The physical connections are clean and solid. There are other related behaviours reported in the past, but I am running Ubuntu 20.10. I guess the attachments will show that I'm using Intel graphics hardware. The monitor is a very popular Samsung one. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: xorg 1:7.7+19ubuntu14 ProcVersionSignature: Ubuntu 5.4.0-73.82-generic 5.4.106 Uname: Linux 5.4.0-73-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.17 Architecture: amd64 BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log' CasperMD5CheckResult: skip CompositorRunning: None CurrentDesktop: ubuntu:GNOME Date: Thu May 20 16:56:04 2021 DistUpgraded: 2020-06-01 15:46:34,953 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process “./xorg_fix_proprietary.py” (No such file or directory) (8)) DistroCodename: focal DistroVariant: ubuntu DkmsStatus: virtualbox, 6.1.16, 5.4.0-73-generic, x86_64: installed EcryptfsInUse: Yes ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: Intel Corporation HD Graphics 5500 [8086:1616] (rev 09) (prog-if 00 [VGA controller]) Subsystem: Lenovo HD Graphics 5500 [17aa:5036] InstallationDate: Installed on 2019-01-24 (847 days ago) InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3) MachineType: LENOVO 20BXCTO1WW ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-73-generic root=UUID=a6081f39-700f-4698-bda4-464e53d9d229 ro quiet splash vt.handoff=7 SourcePackage: xorg Symptom: display UpgradeStatus: Upgraded to focal on 2020-06-01 (353 days ago) dmi.bios.date: 09/13/2017 dmi.bios.vendor: LENOVO dmi.bios.version: JBET66WW (1.30 ) dmi.board.asset.tag: Not Available dmi.board.name: 20BXCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40697 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.modalias: dmi:bvnLENOVO:bvrJBET66WW(1.30):bd09/13/2017:svnLENOVO:pn20BXCTO1WW:pvrThinkPadT450s:rvnLENOVO:rn20BXCTO1WW:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad T450s dmi.product.name: 20BXCTO1WW dmi.product.sku: LENOVO_MT_20BX_BU_Think_FM_ThinkPad T450s dmi.product.version: ThinkPad T450s dmi.sys.vendor: LENOVO version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.102-1ubuntu1~20.04.1 version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.6-0ubuntu0.20.04.1 version.libgl1-mesa-glx: libgl1-mesa-glx 20.2.6-0ubuntu0.20.04.1 version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1.2~20.04.2 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1 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/linux/+bug/1929209/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
