SCP/SSH Transfer Speeds Slow

I have tested my Cox residential connection via speed tests and get near the advertised speeds (150MB/s down, 10MB/s up) on the Cox website and via my Ubiquiti router management application. 

I need to use kerberos enabled scp and ssh to transfer files to a remote server, but the transfer speeds are <500KB/sec in real world tests.

Has anyone seen this issue?

Is VPN a solution? 

Thanks

B