My french skills are sufficient to recognize, that this is exactly the same problem I have. After having rebooted to finalize the update yesterday, the computer refused all network connections, although the network works physically (e.g. ping).
I found, that the avast firewall refused to work, and I was not able to switch it on. A solution should be to allow shared network connections, but this setting was also not possible to do (clicking on the empty checkbox had no effect).
By disabling the avast firewall the computer returned to work perfectly.
This happens on a computer, which runs unchanged since years.
So I would be very disappointed, if the only solution would be to completely wipe off Avast and to install new. Or at least, provide a tool to help wiping. I paid a lot of money over the years for this product so I'm barely willing to spend a lot if time uninstalling manually, switch to the protected mode and looking for several remaining files, then to reinstall, give my credentials etc.
And because this problem pops up now on different computers, it seems not be a personal problem, but to be a problem of a faulty update.
By the way, on the computer of my wife, Avast stated since two days, not to shut down the machine, because Avast is doing an update. I think, this is a similar problem, but stuck on another point.
hoping for a better answer...
Roland