I have a Microsoft Surface Pro 4 tablet, and previously a Surface 3 tablet, and on both of them sync does not work properly.
With the Windows 10 64 bit default build, after I reboot (to ensure that all services and processes are totally restarted), initially I will get a sync transfer speed commensurate with a Wireless N connection - approx. 60-80Mb/sec (as monitored in task manager). However, after a period of time Plex becomes convinced that my network connection is crap and drops the transfer speed down to 0.1Mb/sec! The files get flagged with a network transfer error as well.
I sync to a 200GB class 10 external micro SD card and am able to copy files to it from the same server on my local network at 8MB/sec so the card is not the throttle. I also previously moved my sync location back to the SSD but had the same issue.
On other laptops in the house, this drop off in sync speed does not happen!
This has been reported multiple times before in a number of threads e.g. https://forums.plex.tv/discussion/253887/plex-sync-stops-working-after-2-or-3-videos#latest but has yet to even be commented on!
I have paid for a service which is fundamentally flawed, and I would at least like some acknowledgement that this issue is being looked at...
I enclose the networking diagnostic log files from my last attempt to sync which successfully synced 1 file at full speed, and then during the second dropped back to 0.1 Mb/sec.
If you require any further information, please just ask! I am more than happy to conduct any further tests of code or diagnostics to track down this VERY annoying issue.