2012 iMac connectivity issues

Hello. So my iMac is losing internet while everything else remains connected. The only way to regain connection is by restarting the Mac. And a lot of the times, doing this will cause it to freeze, resulting in a hard reset.

It seems to lose connection over night while the machine is either asleep or downloading big files. No matter how many times you click the WiFi icon to turn on/off, it will not regain connection without restarting. Thanks!