Had the same issue since I updated to Big Sur. Spoke to Apple Support several times before finding Demona. She had a pretty simple solution to the problem. Here it goes: ====== We are going to create a New Network Location starting with booting to safe mode. 1 Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up. 2 Release the key when you see the login window, then log in to your Mac. 3 You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window. Once that is completed, 1 Open System Preferences > Network. 2 On the 'Locations' drop down, select 'Edit Locations'. • Note: If the Network pane is locked, you must unlock it first. 3 Click the '+' button to create a new location. 4 Give the new location a name and click 'Done'. 5 Make sure the new location is selected in the 'Locations' drop down menu and click 'Apply'. ===== And just like that, everything started working smoothly once again. Demona Rocks. Be like Demona!