@deesnow Ok, since I have lost my magic crystal-ball I will ask you a few questions, for someone to be able to help you:
1 - What version of DSM and bootloader did you upgrade from?
2 - Do you use DS3615 / 3617 / 916 / 918? Did you change this during your upgrade?
3 - What type of NIC do you have, and what driver is it using?
4 - Do you have any additional packages installed? (if so, did you install them before or after the upgrade?)
5 - next Q will follow later