I run 2.5Gbps on cat5e no problem.
What gear do you use for this?
Sonicwall with 802.11ac wave2 mu-mimo, mostly it seems to help with contention. Kids rooms are not wired so they use wifi - for gaming they are not seeing the lag issues.
Sorry, I meant what gear are you running 2.5gbps over cat5e? Are you using expensive proprietary Cisco stuff - which is all I could find on Google.