Debian 9 repos down?

Hi! I have just installed Debian 9 and, following the wiki, tried to install tinity, but when I run apt-get update (or apt update), I get: ---- Err:8 http://mirror.xcer.cz/trinity-sb stretch/deps-r14 Sources 403 Forbidden [...] Reading package lists... Done W: The repository 'http://mirror.xcer.cz/trinity-sb stretch Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. E: Failed to fetch http://mirror.xcer.cz/trinity-sb/dists/stretch/deps-r14/source/Sources 403 Forbidden E: Some index files failed to download. They have been ignored, or old ones used instead. ---- I tried to access to http://mirror.xcer.cz/trinity-sb with firefox, and I get a "Forbidden" error. Are there any mirrors I can use? Thanks in advance, -- Diego.