12 MB/s or 12 Mb/s?
If it's 12 MB/s it's pretty much exactly the throughput of a 100 Mb/s link (12.5 MB/s) so I assume some part of the chain in your network is degraded to 100M because of poor quality cables for example (you need CAT5E or better for a gigabit network).
It's 12Mb's. I was before last month or so of updates 120mb. Nothing else has changed.