I’ve repeatedly had issues on runs between 50 and 100 feet with cat 5. Lots of spooled ethernet cable has out-of-spec twist rates and shit that affect performance you won’t notice until you’ve done longer runs. They’re fine for the standard 6-12 feet most people do from the PC tothe wall, but when you do a longer run up the wall, through the attic, and back down another wall and you start having problems.