How to get eth0 and wlan0 back on Ubuntu Mate 18.04?

[Tom H]

On Sun, Jan 31, 2021 at 12:41 AM Ralf Mardorf via ubuntu-users
<ubuntu-users at lists.ubuntu.com> wrote:
> On Sun, 2021-01-31 at 00:12 +0100, Bo Berglund wrote:
>>
>> Do I have to reboot the laptop for it to take effect or is there
>> some quicker way to make it happen?
>
> Yesno. It's possible to change kernel parameters at runtime, using
> sysctl, if they are listed by running
>
>   sudo sysctl -a

I didn't think of using sysctl, but changing "99-default.link"
should've done it if were possible. I wonder whether you can set
"net.ifnames" anywhere other than at the kernel cmdline for it to be
useful given that this is the only upstream recommendation, other than
changing the udevd config.