Trying to download 25.2.3. The download times out.
https://portableapps.com/apps/office/libreoffice_portable
I went directly to SourceForge. The files are missing from the LibreOffice folder
https://sourceforge.net/projects/portableapps/files/LibreOffice%20Portable/
Some publishers host their own apps, just like Inkscape.
Go to the the LibreOffice official download page, and search for → Archives.
'Joy is ephemeral, live it before realizing the truth'
― Neo Buddha ―
In the case of LibreOffice, they say to get them from PortableApps.
https://www.libreoffice.org/download/portable-versions/
Their downloads time out, too. Likely because the files are missing from SourceForge.
LibreOffice is hosted by the publisher on a global network of download servers. The same servers you download the local version from. Every version except legacy versions work this way. It looks like your local download mirror is having issues. It should resolve itself or you can report it to the LibreOffice team.
Sometimes, the impossible can become possible, if you're awesome!