[RESOLVED] Internet is not working after upgrading to Kubuntu 24.04

[boxcorner]

Hello

I hope this is the right place to ask for help following upgrade to Kubuntu 24.04.2 LTS

There used to be an icon at the bottom of the screen showing Networks or WiFi signal strength.
The icon is not in hidden icons.

When I try to start Thunderbird I get a page with an 'octopus' asking me to 'Set Up Your Existing Email Address'.

When I start Firefox it says 'Server NotFound'.

I presume this is a configuration problem.

I did a backup shortly before I upgraded to 24.04 .

Could someone please tell me what I need to do to get Kubuntu working with Internet access?

My computer is an Intel NUC8i3BEH2

I had an Internet repeater connected to the computer via Ethernet cable.
The repeater is connected to a router wirelessly.
I have disconnected the repeater by unplugging the Ethernet cable.
I have rebooted the computer since I disconnected the repeater.

Software KDE Plasma Version 5.27.12
KDE Frameworks Version 5.115.0
Qt Version 5.15.13
Kernel Version 6.8.0-53-generic (64 bit)
Graphics Platform X11

Thank you, in advance. 🙏


ADDENDUM - what I have done
=========================
I reconnected the Ethernet cable from the WiFi repeater.

I found a bootable USB key for version 20.04
That enabled me to boot Kubuntu, to try 20.04 & run to Firefox with Internet access.

That enabled me to download kubuntu-24.04.2-desktop-amd64.iso
So I could create a bootable USB for Kubuntu 24.04.2 LTS 64-bit

When I boot 24.04 from the USB key to try Kubuntu that too enables me to access the Internet via Firefox.
However the installed version 24.04 on my hard drive does not.

The installed version 24 works perfectly in every other respect, including printing, but not Thunderbird.
When I try to start Thunderbird I get a page with an 'octopus' asking me to 'Set Up Your Existing Email Address'.

I don't know how to configure the network to get Internet access.

I'm considering installing version 24 from the bootable USB key.

There's a minimum installation option, but I'm worried about messing up what's on my hard drive & what works.

The alternative would be install version 20 from bootable USB key & restore data from my last backup.
I'm not sure whether that's the best way to roll back from version 24 to 20.

Any comments would be welcome ...
Thank you, in advance. 🙏


ADDENDUM - what I have done
=========================
I tried
$ sudo systemctl restart NetworkManager
Got this
Failed to restart NetworkManager.service: Unit NetworkManager.service not found.

UPDATE
=======
I downloaded the .iso file for version 22 & created a bootable USB key via System > Startup Disk Creator
I booted version 22 and tried it
It worked, including both Wired Ethernet & Wi-Fi
I decided to do a full installation
With version 22 installed both Wired Ethernet & Wi-Fi worked
So I decided to try upgrading to version 24
Having upgraded to version 24, both Wired Ethernet & Wi-Fi work
Conclusion
=========
Upgrading from version 20 to 24 resulted in loss of Internet access
Upgrading from version 22 to 24 works without loss of Internet access
Now I will try to recover data from the backup that I did before I upgraded from 20 to 24
I need to find how to recover my emails to restore Thunderbird
& I need to find how to recover URLs that I saved when using Firefox, plus other stuff

[Qqmike]

I'm not a network expert at all. You have tried what I usually do: unplug/re-boot everything! (PC, Modem, whatever).
There are lots of comments about Internet issues around here lately.

I'm considering installing version 24 from the bootable USB key.

Yes! Why not!? A clean install. But as you indicate, be careful not to mess up any existing stuff related to your use of 24.04.
You mention 20.04. How about 22.04? I'm still on 22.04 and so far it's working great.

[boxcorner]

Many thanks for your reply & moral support.
I see now that other people are reporting Internet issues.
Yes, 22.04 more tried & tested would be more sensible.