I've installed an Netgear Wi-Fi 6 Mesh for improved Ethernet access security. Windows 11 (64-Bit), and all applications including browsers (Edge and Firefox) work without issues. CCleaner Pro v6.07.10191 (64-Bit) is the exception, and the issue is extremely odd, e.g.: 1) Cleaning and version updating work as expected; 2) Application updater does not; It fails and gives the message "No internet connection." All attempts to resolve this issue have failed. Have other users experienced a similar failure. I request and welcome your support.
I believe that the message is not actually saying what the issue is, or at least not fully.
There are a few 'unclear' messages like that in CCleaner, and in most other softwares.
There is only so much text you can put in such messages, so they can tend to be a bit general or vague.
What will be happening is that your security (probably the firewall, possibly a Hosts file) is blocking access to the particular server that the updater is trying to reach.
The software only knows that the connection isn't being made, it doesn't/can't know why not, so the message suggests the most likely reason ie. that there is no internet connection.
But that doesn't mean that you don't have an internet connection at all, just that you dont have an internet connection to the required server (because it's being blocked).
You may find that one or more of the Software Updater, CCleaners own automatic updating, and possibly the Performance Optimiser also won't work.
Each one has to contact a different server to do it's job and those contacts may also be being blocked.
Health Check's Speed and Security (the Software Updater tool) may also be being blocked, but if one is it will say the slightly more accurate 'Unable to reach server'
TBH You shouldn't need to use the Driver Updater with Win 11 anyway. (Personally I wouldn't use any Driver Updater at all).
If you do want to then you will need to find out which part of your security is blocking the connection(s), and make that connection an exception/allowed in the security.
Alternatively you could temporarily pause/disable the security while using the Updater, don't forget to turn it back on again.
I get this error with software updater when I have my VPN running. Turning the VPN off while the Software Updater is scanning allows it to work.