Refer to https://bbs.archlinux.org/viewtopic.php?id=224683 for more info. Additional info: * plasma-nm 5.9.4-1 Steps to reproduce: 1. Edit any Wi-Fi connection, the changes can be saved. 2. Edit any Ethernet connection, the Save/Apply button has been greyed out, changes cannot be saved. 3. For Ethernet connection, changes can be saved using nmtui.
Should be fixed by https://cgit.kde.org/plasma-nm.git/commit/?id=47599d8b03e5e7b4978e19acb90da38a01d41aff or related https://cgit.kde.org/networkmanager-qt.git/commit/?id=d039943788dd08a5e2b1611732e3cfb6c2f64f26 workaround in the meantime is to manually select 'Allow auto-negotiation' option *** This bug has been marked as a duplicate of bug 378554 ***