So what is the difference between TCP and UDP you might ask. UDP just streams the data to your device and vice versa and it records what you are getting. TCP on the other hand has checksums and a lot of other things going on in the background to make sure that all the packets are getting there and it doesn't have to resend any packets etc. Couple of things to check since you are running new code have you checked the drivers for your nics to make sure they are the latest and support some of the new features that are in that code. We have had issues with new features and during an upgrade something gets turned off bye default that was previously turned on so check your configs.