Default installer offer the site in the installation of OS process is: ftp://ftp1.de.freebsd.org/pub/freebsd/snapshots/i386/i386/11.0-CURRENT/ But this link is broken. You have to delete "pub". So the correct link should be as: ftp://ftp1.de.freebsd.org/freebsd/snapshots/i386/i386/11.0-CURRENT/ By the way, there are several ftp2, ftp4, ftp5 sites but ftp1 is absent. Even if I am wrong on the last point, please check which ftp is update and add if it is necessary.
Affects installer.