Help with some strange IPerf Results

I am getting some strange IPerf results, hoping someone might be able to help with why this might be. Initially I thought it was only traffic over the site to site VPNs. But i am actually getting the same speeds across my entire Datacenter. This is across the VPNs and straight out to public IPerf servers.

Example Snippets:

Site to Site VPN

[ ID] Interval Transfer Bandwidth

[ 4] 0.00-1.01 sec 5.17 MBytes 42.8 Mbits/sec

[ 4] 1.01-2.01 sec 5.54 MBytes 46.5 Mbits/sec

[ 4] 2.01-3.01 sec 5.35 MBytes 45.0 Mbits/sec

Same site to Internet

[ 4] 0.00-1.01 sec 5.04 MBytes 41.7 Mbits/sec

[ 4] 1.01-2.01 sec 5.48 MBytes 46.0 Mbits/sec

[ 4] 2.01-3.01 sec 5.48 MBytes 46.0 Mbits/sec

Opposing site to internet, slightly better

[ 4] 0.00-1.00 sec 9.84 MBytes 82.2 Mbits/sec

[ 4] 1.00-2.00 sec 10.2 MBytes 85.5 Mbits/sec

[ 4] 2.00-3.00 sec 10.2 MBytes 85.6 Mbits/sec

I have asked the DC and they claim there is no restrictions. We have 500Mbps lines. So these speeds are actually terrible. Any advice appreciated.