If you are using an NSS version prior to version 3.1 you should update ASAP.
Thermo fixed a bug in their NSS v. 3.1 TCP/IP stack that was causing some isolated comms reliability issues on very long automated runs. Version 3.2.298 or so will be released soon and that will also have this fix.
FYI: I just tested Thermo NSS 4 with PFE using the TE Portal API everything seems to work fine on my laptop under Win 10.
john