Where can I download Windows 2.3.3 client?

I updated my windows client from 2.3.3 to 2.5.1 recently. After the update, I keep getting “An error occurred while opening a folder Network access is disabled.” message. My other PC has not been updated and does not have this issue. Is there a way I can reinstall 2.3.3 client?

Of course you can uninstall the client and reinstall the older version. I can’t tell you if it’s the solution to your problem.
Here you can also find the older version:

Don’t forget to report this issue on the bugtracker https://github.com/nextcloud/desktop/issues to make sure they fix this problem in the next version.

Same issue for me - also done fall-back to Win client against server 15.0.7