While installing Manjaro i3, during the install it stopped and acted as if I had no internet connection so I plugged out my ethernet cable and plugged it back in, i regained a connection long enough for the install to finish but when I finally got into actual Manjaro my internet did not work. Pinging sites would only give back that the destination host was unreachable. Plugging my ethernet cable out and back in did not give me a connection for a short time either.
I had this problem while using a TUI to install Arch as well, it said i was not connected to the internet. I was going to install Debian to see if I had the same problem on that but my USB drive seems to be corrupted or something as I cant format it or flash anything with uNetbootin or balenaEtcher.