Ubuntu 18.04: No USB, WLAN, HDMI after upgrading kernel

My situation:

I upgraded the firmware of my Lenovo T480 (via Ubuntu’s “application store”) and everything went fine except that I was running 4.18 kernel before and now it did not boot anymore due to some signature problem (Secure Boot is enabled). No problem, I just selected 4.15 from boot menu and it still worked (why?).

So, I installed the newest 5.0.0-27. However, after reboot I noticed that USB didn’t work, WLAN didn’t and even the external display didn’t work anymore. Then I installed 4.17. Same problem. It seems that only the default 4.15 now works.

Any ideas what has happened?

There are no errors when installing the other kernels. It’s just after reboot I’m lacking USB, WLAN and HDMI. Otherwise the kernels seem to work.

Is it possible to dc someones internet without WLAN running

I’m using a FRITZ!Box Router (with updated OS) and behind the NAT there are only devices via wired LAN connected. Actually there is only one device connected! It’s my notebook with a renewed HDD and reinstalled OS (linux).

I would like to know if it could be possible to force a disconnect from outside of my subnet. My notebook’s WLAN adapter was activated, but not connected. WLAN on my router is turned off due to abnormal behaviour in past. A few years back there were no problem. Since 1 year I got that weird stranger in my neighborhood, who stalks me and the disconnections conspicuously increased. Since I switched to wired LAN no unexpected dc noticed anymore…

I’m unexperienced and don’t know much about the possible attacks on routers or connected computers. I’m actually still learning much about web security (according to smartphones and pcs) and maybe we talk about bad coincidences, but I would like to know, if it could be possible, that attackers were able to compromise my home net or still could use possibly weak points like activated wifi adapters from notebooks to hoax me with disconnections or possibly more like spying activities.

no connection with Broadcom BCM4311 802.11b/g WLAN wireless card

Since I installed Lubuntu 18.04.3 recently (on a Lenovo 3000 N-100 notebook) I have no wireless connection. I’ve read several previous AskUbuntu questions. Regarding the first answer to the AskUbuntu question at https://askubuntu.com/questions/55868/installing-broadcom-wireless-drivers, I believe I followed the section titled Installing The Package (Online). There is still no wireless connection. Here is a current screenshot of the system tool Software and Updates. enter image description here

If you can help with suggestions, please make them clear and complete, step-by-step, without unnecessary assumptions/jargon/etc as I’m relatively new to Linux, and my awareness of system architecture and software is quite limited. Thank you.

Capturing multicast packets in WLAN

(I had to move this from Network Engineering stack exchange where I origianlly asked this question)

If a device in monitoring mode snoops on the traffic in a WLAN, can it CAPTURE and READ multicast packets?

For instance, if a device broadcasting packets to multicast address, can a monitoring device capture and read those packets?

wlan off when turning on computer

sometimes when I turn on my laptop its on flight mode, when I turn off flight mode Bluetooth is turned on. ifconfig says device not found, i.e I cant connect to the internet. if I restart the computer it solves the problem. I am very curious about why this is happening and especially why it only happens approximately 1 out of 10 times. How can I find out?


Access router from guest WLAN as if from outside

I configured RouterOS on RB2011UiAS-2HnD-IN‎ to have 2 WLANs: the primary, as a LAN interface, and the guest WLAN, with isolation using firewall drop rule. Guest WLAN can access Internet, but not the LAN. Now, I have a Jabber server in the network. All the NAT rules are set up so that it is accessible from outside + a hairpin NAT rule to access it from LAN. Everything is working fine until I attempt to connect a guest net device to Jabber. My logic is so that if a device can access the Internet, it should also be able to access the router as if from outside. How to achieve this?

TP-Link Archer T2U V2 can not connect to WLAN on Ubuntu 19.04

I’m trying to connect to my home wifi. Plasma indicates that a connection is being established (rotating circle), and then fails to connect.

uname -a:

Linux hostname 5.0.0-15-generic #16-Ubuntu SMP Mon May 6 17:41:33 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux 


[   24.328693] usb 2-1.2: new high-speed USB device number 3 using ehci-pci [   24.462471] usb 2-1.2: New USB device found, idVendor=148f, idProduct=761a, bcdDevice= 1.00 [   24.462476] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [   24.462479] usb 2-1.2: Product: WiFi [   24.462482] usb 2-1.2: Manufacturer: MediaTek [   24.462484] usb 2-1.2: SerialNumber: 1.0 [   25.009613] cfg80211: Loading compiled-in X.509 certificates for regulatory database [   25.015016] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7' [   25.128668] usb 2-1.2: reset high-speed USB device number 3 using ehci-pci [   25.247582] mt76x0u 2-1.2:1.0: ASIC revision: 76100002 MAC revision: 76502000 [   26.654170] mt76x0u 2-1.2:1.0: EEPROM ver:02 fae:01 [   27.230757] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht' [   27.231175] usbcore: registered new interface driver mt76x0u [   27.243913] mt76x0u 2-1.2:1.0 wlx503eaab994d1: renamed from wlan0 [   35.404273] wlx503eaab994d1: authenticate with f4:06:8d:c9:3b:24 [   35.855337] wlx503eaab994d1: send auth to f4:06:8d:c9:3b:24 (try 1/3) [   35.857284] wlx503eaab994d1: authenticated [   40.993891] wlx503eaab994d1: authenticate with e0:28:6d:3d:54:5c [   41.423843] wlx503eaab994d1: send auth to e0:28:6d:3d:54:5c (try 1/3) [   41.430296] wlx503eaab994d1: authenticated [   51.274859] wlx503eaab994d1: authenticate with f4:06:8d:c9:3b:24 [   52.180228] wlx503eaab994d1: send auth to f4:06:8d:c9:3b:24 (try 1/3) [   52.186147] wlx503eaab994d1: authenticated [   58.217434] wlx503eaab994d1: authenticate with e0:28:6d:3d:54:5c [   58.672672] wlx503eaab994d1: send auth to e0:28:6d:3d:54:5c (try 1/3) [   58.796502] wlx503eaab994d1: send auth to e0:28:6d:3d:54:5c (try 2/3) [   58.802071] wlx503eaab994d1: authenticated [   68.127196] wlx503eaab994d1: authenticate with f4:06:8d:c9:3b:24 [   68.559101] wlx503eaab994d1: send auth to f4:06:8d:c9:3b:24 (try 1/3) [   68.562722] wlx503eaab994d1: authenticated [   69.520564] mt76x0u 2-1.2:1.0: rx urb failed: -71 [   69.525171] mt76x0u 2-1.2:1.0: rx urb failed: -71 [   69.530077] mt76x0u 2-1.2:1.0: rx urb failed: -71 (same message repeated ~40 times) [   69.759192] mt76x0u 2-1.2:1.0: rx urb failed: -71 [   69.763706] mt76x0u 2-1.2:1.0: rx urb failed: -71 [   69.764546] mt76x0u 2-1.2:1.0: vendor request req:07 off:1134 failed:-71 [   69.768568] mt76x0u 2-1.2:1.0: rx urb failed: -71 [   69.770807] usb 2-1.2: USB disconnect, device number 3 [   69.779197] mt76x0u 2-1.2:1.0: mac specific condition occurred 

not able to see the devices connected to my home WLAN network

I ve tried on my laptop the utility advanced port scanner, I ve tried on my android phone the utility fing. Both utilities only show the computer, on which they are running, and the network router dv2210. But not the other computers in the home network. Why?

I ve tried this advice:


but on my router this AP Isolation is off

What could be the problem?