unstable internet. Rollback from linux-libc-dev 4.40-186.216 ?

[XP-refugee]

I've just used Update Manager and updated
linux-libc-dev 4.40-186.215 to linux-libc-dev 4.40-186.216
snapd 2.45.1 to snapd ubuntu0.2
firefox-locale-en 78.0.1+linuxmint1+sylvia to firefox-locale-en 78.0.2+linuxmint1+sylvia
firefox 78.0.1+linuxmint1+sylvia to firefox 78.0.2+linuxmint1+sylvia
libldap-2.4-2 2.4.42+dfsg-2ubuntu3.8 to libldap-2.4-2 2.4.42+dfsg-2ubuntu3.9

And now this machine's internet connection is unstable. (Another device is connecting through the same router nicely.

My wild guess is that I need to roll back to linux-libc-dev 4.40-186.215
But

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sudo apt-get install linux-libc-dev 4.40-186.215 

gives

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E: Unable to locate package 4.40-186.215
E: Couldn't find any package by glob '4.40-186.215'
E: Couldn't find any package by regex '4.40-186.215'

Any help from wiser users will be appreciated.

[zcot]

That looks like a pretty wild ride!

To specify a version of a package the format is <package_name>=<package_version_name>.

[XP-refugee]

Thanks zcot.

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sudo apt-get install linux-libc-dev=4.40-186.215

gets me

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Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Version '4.40-186.215' for 'linux-libc-dev' was not found

My internet connection remains unstable - a ping-time table is only half filled on this device whereas here-there times are all filled in on other devices connecting over the same router.

[zcot]

I would get with Jeremy on IRC to do some realtime diagnostics. Or formulate a good post on the forum here strictly mentioning the connection and the system data to go with it.

But as far as tinkering around with packages, that package version is not correct. I don't know where you got that version number but you'll have to use the exact appropriate one, and furthermore it's not just the version number you add, it's the versioned name of the package, you are specifying a certain exact package. Sometimes the version might be 1.2, but the package version name is actually 1.2-0ubuntu-5.2, so you can get the exact name with some apt or package searches or whatever and it will be correct.

[XP-refugee]

What you write in your last post is way beyond my understanding.

[zcot]

here is an ubuntu package search for linux-libc-dev and various versions are listed: https://packages.ubuntu.com/search?keyw ... x-libc-dev

[XP-refugee]

zcot what you write is way beyond my technical level.

I guess that that search shows me the list of the current linux-libc-dev packages.
That would make sense of Update Manager History showing me that I updated from linux-libc-dev 4.40-186.215 to linux-libc-dev 4.40-186.216

But how to downgrade to linux-libc-dev 4.40-186.215, and whether I need
xenial (16.04LTS) (devel): Linux Kernel Headers for development 4.4.0-186.215 [security]: amd64 i386
or
xenial-updates (devel): Linux Kernel Headers for development 4.4.0-186.215: amd64 arm64 armhf i386 powerpc ppc64el s390x
, if that is what is needed, remains a mystery.

With a google search for

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linux-libc-dev 4.40-186.215

returning nothing beside this thread, I suspect that I'm not approaching this the right way.

[zcot]

I think the version string is wrong in one of these searches:

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linux-libc-dev 4.40-186.215

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linux-libc-dev 4.4.0-186.215

[XP-refugee]

Yes.
Error in "linux-libc-dev 4.40-186.215 to linux-libc-dev 4.40-186.216"

Update Manager History has
linux-libc-dev 4.40-185.215 to linux-libc-dev 4.40-186.216
with 185.215 both ending in 5, and 186.216 both ending in 6.