Do you have the connection settings of the network card on Auto/Auto or on 1GBps fixed ?
Sometimes NIC and Switch/router don't communicate correctly, setting it fixed when it's on auto or the other way around helps.
Is the Cable the same as always (in other words , did it work with same setup last week or is it a new machine/router/nic etc ?)
Did you install any new software updates ?
I remember on my download machine last week i had exactly 1.13MB/s (Byte that is), so 10Mb (small letter b) per second. Looked into the properties and after the last Microsoft update my NIC was set to 10Mbps instead of 1Gbps. Setting it back to Gigabit fixed it...
Maybe you can use this info ?
I didn't fail !
I just found out 10,000 ways that didn't work.