All my devices at home* are dual-stack and so are some of the servers I run. Never had any issues. Browsers, ssh/sftp, nginx, whatever's behind nginx, Exim... n

All my devices at home* are dual-stack and so are some of the servers I run. Never had any issues. Browsers, ssh/sftp, nginx, whatever's behind nginx, Exim... no complications beyond adding another listen line to the configuration where appropriate. * Except Kindles.