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I'm currently using Ubuntu 18.04.1, with kernel version 5.3.0-40.

I need to downgrade to kernel 4.15.x to use my work VPN application.

I downloaded the older kernel version and booted into it, but then I have no connection in there (neither with LAN or with wi-fi). I guess it's a driver problem, but since I'm a newbie to the world of Linux I really don't know what to do even after searching online for a bit.

Any help would be really appreciated, thank you.

Edit:

apt list --installed | grep ^linux output

dmesg output `

lspci output

lsusb output

user9361548
  • 121

3 Answers3

3

I had a similar problem where my cellular modem was not being recognized after downgrading my Ubuntu Linux kernel.

To solve my problem, I had to ensure the following modules-extra package was also installed: linux-modules-extra-5.4.0-42-generic

I had previously only installed the following:

sudo apt-get -y install \
linux-image-5.4.0-42-generic \
linux-headers-5.4.0-42-generic \
linux-modules-5.4.0-42-generic

The following command is helpful for checking which packages are installed:

dpkg -l | grep "linux-"

ii  binutils-x86-64-linux-gnu                  2.34-6ubuntu1.1                       amd64        GNU binary utilities, for x86-64-linux-gnu target
ii  linux-base                                 4.5ubuntu3.5                          all          Linux image base package
ii  linux-firmware                             1.187.15                              all          Firmware for Linux kernel drivers
ii  linux-generic-hwe-20.04                    5.8.0.59.66~20.04.42                  amd64        Complete Generic Linux kernel and headers
ii  linux-headers-5.4.0-42                     5.4.0-42.46                           all          Header files related to Linux kernel version 5.4.0
ii  linux-headers-5.4.0-42-generic             5.4.0-42.46                           amd64        Linux kernel headers for version 5.4.0 on 64 bit x86 SMP
ii  linux-headers-5.8.0-43-generic             5.8.0-43.49~20.04.1                   amd64        Linux kernel headers for version 5.8.0 on 64 bit x86 SMP
ii  linux-headers-5.8.0-59-generic             5.8.0-59.66~20.04.1                   amd64        Linux kernel headers for version 5.8.0 on 64 bit x86 SMP
ii  linux-headers-generic-hwe-20.04            5.8.0.59.66~20.04.42                  amd64        Generic Linux kernel headers
ii  linux-hwe-5.8-headers-5.8.0-43             5.8.0-43.49~20.04.1                   all          Header files related to Linux kernel version 5.8.0
ii  linux-hwe-5.8-headers-5.8.0-59             5.8.0-59.66~20.04.1                   all          Header files related to Linux kernel version 5.8.0
ii  linux-image-5.4.0-42-generic               5.4.0-42.46                           amd64        Signed kernel image generic
ii  linux-image-5.8.0-43-generic               5.8.0-43.49~20.04.1                   amd64        Signed kernel image generic
ii  linux-image-5.8.0-59-generic               5.8.0-59.66~20.04.1                   amd64        Signed kernel image generic
ii  linux-image-generic-hwe-20.04              5.8.0.59.66~20.04.42                  amd64        Generic Linux kernel image
ii  linux-libc-dev:amd64                       5.4.0-77.86                           amd64        Linux Kernel Headers for development
ii  linux-modules-5.4.0-42-generic             5.4.0-42.46                           amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
ii  linux-modules-5.8.0-43-generic             5.8.0-43.49~20.04.1                   amd64        Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP
ii  linux-modules-5.8.0-59-generic             5.8.0-59.66~20.04.1                   amd64        Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP
ii  linux-modules-extra-5.4.0-42-generic       5.4.0-42.46                           amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
ii  linux-modules-extra-5.8.0-43-generic       5.8.0-43.49~20.04.1                   amd64        Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP
ii  linux-modules-extra-5.8.0-59-generic       5.8.0-59.66~20.04.1                   amd64        Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP
ii  linux-sound-base                           1.0.25+dfsg-0ubuntu5                  all          base package for ALSA and OSS sound systems
Sean McCarthy
  • 139
0
sudo apt install --reinstall linux-generic linux-image-generic  linux-headers-generic

linux-generic points to linux-image-generic (points to newest available 4.15. kernel line) and linux-headers-generic (the same but for kernel-headers)

nobody
  • 5,792
0

I ran into a similar issue with Ubuntu 20.04, downgrading from 5.8 to 5.4 kernel.

I think the answer for 18.04 is similar to @nobody's answer, but you want to specify a slightly different package naming:

sudo apt install linux-generic-hwe-16.04

That one will pull in some things that are needed, along with the 4.15 kernel, though I didn't dig to find further what those things actually are. (the hwe-18.04 package would pull in the mainline kernel for 18.04, which was 5.3 and is now 5.4, I believe)

For completeness, you may want to also install other packages of that sort, namely:

sudo apt install linux-generic-hwe-16.04 \
    linux-headers-generic-hwe-16.04 \
    linux-image-generic-hwe-16.04

You may also in this scenario want to prevent upgrades to any major kernel above 4.15. You can do that by putting an apt-mark hold on the hwe-18.04 packages. More on that in my answer to this question about holding back the Linux kernel on Ubuntu.

Gertlex
  • 550