To do so on a PC:
- Close the MTG Arena client.
- Open a Windows command prompt (cmd.exe) as an administrator.
- Type ipconfig /flushdns and press enter.
- Type ipconfig /registerdns and press enter.
- Type ipconfig /release and press enter.
- Type ipconfig /renew and press enter.
- Type netsh winsock reset and press enter.
- Restart your computer and launch the MTG Arena client.
To do so on a Mac:
- Open a terminal window from Applications > Utilities. You could also press Command + Space and searching for Terminal.
- From there, input the command for flushing your cache. The command you use is different depending on your Mac OS version.