For some years I am using an external display via a Thunderbolt 3 dock on my Dell XPS laptop. It always worked nicely and also after the upgrade to Fedora 43. However after an update of KDE several months ago, the external display stopped working. The display works when unlocking luks and the KDE login window screen is also shown on that external display. But after logging in, the display goes blank and switches off. In the display section of KDE I can’t enable it and it reports something about a gap between the displays. However, in the arrangement panel there is only the internal display. Other pheripherals like the mouse, keyboard or the external DAC work normally and are connectend via the Thunderbolt dock.
uname -a
Linux boromir 6.17.12-300.fc43.x86_64 #1 SMP PREEMPT_DYNAMIC Sat Dec 13 05:06:24 UTC 2025 x86_64 GNU/Linux
System info
Operating System: Fedora Linux 43
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.21.0
Qt Version: 6.10.1
Kernel Version: 6.17.12-300.fc43.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 12 × Intel® Core™ i7-8750H CPU @ 2.20GHz
Memory: 16 GiB of RAM (15,2 GiB usable)
Graphics Processor 1: Intel® UHD Graphics 630
Graphics Processor 2: NVIDIA GeForce GTX 1050 Ti with Max-Q Design
Manufacturer: Dell Inc.
Product Name: XPS 15 9570
lsmod | grep -i nou
nouveau 3985408 0
drm_ttm_helper 16384 1 nouveau
gpu_sched 69632 1 nouveau
drm_gpuvm 49152 1 nouveau
drm_exec 12288 2 drm_gpuvm,nouveau
i2c_algo_bit 20480 2 i915,nouveau
ttm 135168 3 drm_ttm_helper,i915,nouveau
mxm_wmi 12288 1 nouveau
drm_display_helper 331776 2 i915,nouveau
video 81920 4 dell_wmi,dell_laptop,i915,nouveau
wmi 32768 10 dell_wmi_sysman,video,intel_wmi_thunderbolt,dell_wmi,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor,mxm_wmi,nouveau
Can someone help me further with this problem? Thanks in advance.