Did you try connect using Ethernet or WiFi?
If WiFi is not working then most probably the problem is missing firmware in the sys-net template.
What template did you select for your system qubes during initial setup? Debian or Fedora?
If the problem is missing firmware then you’ll need to do this:
Download the latest firmware from some other system, copy it on some USB drive, then in Qubes OS copy the firmware files to your sys-net template.