After debug, this issue is not related to kernel. cdc_ether was unregistered by usb-modeswitch. After I installed the old verison of usb-modeswitch, this issue is fixed, it looks like a regression.
Aug 30 05:54:32 u-ThinkPad-L460 kernel: cdc_ether 1-9:2.0 wwan0: register 'cdc_ether' at usb-0000:00:14.0-9, Mobile Broadband Network Device, 02:1e:10:1f:00:00 Aug 30 05:54:32 u-ThinkPad-L460 kernel: usbcore: registered new interface driver cdc_ether Aug 30 05:54:32 u-ThinkPad-L460 kernel: cdc_ether 1-9:2.0 wwx021e101f0000: renamed from wwan0 Aug 30 05:54:33 u-ThinkPad-L460 kernel: cdc_ether 1-9:2.0 wwx021e101f0000: unregister 'cdc_ether' usb-0000:00:14.0-9, Mobile Broadband Network Device -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1940377 Title: The WWAN - Huawei Technologies Co., Ltd. [12d1:15c1] does not work after install Ubuntu Hirsute. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1940377/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
