So having recently set up my Synology 1813+ NAS with link aggregation to a Netgear GS110TP switch with 9KB jumbo frames enabled, I was getting excruciatingly slow upload speeds from my PC to a file share on the NAS. To be precise, I was only getting upload speeds between 35 – 45 MB/s, quite unacceptable given my hardware and network configuration.
After many days of troubleshooting, I was able to nail down the culprit to these two programs:
- Directory Opus 10.5.4.0 (5080) – Note: this is an Explorer replacement
- Symantec Endpoint Protection 12.1.4013.4013 – Note: the specific offending module is called “Network Threat Protection”
Tuning Step 1
Note: for this step, I disabled Symantec Endpoint Protection.
First, I tuned Directory Opus by adjusting the copy_buffer_size setting under Miscellaneous -> Advanced. The default value is 6KB which was way too small. By gradually increasing this value, you can see in the graph below that my throughput increased as well, until hitting a maximum and gradually tapering off. The optimal setting for me turned out to be 512KB, which practically doubled my PC-to-NAS speed.
Tuning Step 2
Next up, was to disable the Symantec Endpoint Protection’s Network Thread Protection (SEPNTP) module. I was never able to fully narrow down the setting in this module that caused my transfer speeds to drop, but what I did notice was that with this feature turned on, transfer speeds could fluctuate between anything from 20-40% slower. There was no pattern at all. For e.g. after implementing Step 1 above, with SEPNTP enabled, my PC-to-NAS copy speeds could sometimes drop to as low as 50-70+ MB/s.
I think this is too big a penalty to pay so promptly disabled SEPNTP and downloaded ZoneAlarm Basic for my software firewall needs.