To rule out something, have you tried both of these options, in regards to the server:
- Use a different cable (or borrow one from a “good” client connection) [1]
- Use a different port on the switch
I think you mean CAT5e, since CAT5’s maximum is 100 Mbps.
How long is the cable?
A loose connection or fraying head can cause slower speeds, even if the connection appears to be “working fine”. ↩︎