Internal network speed - In general but between 2 Synologies

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Internal network speed - In general but between 2 Synologies

DS918+, DS215+
I am about to upgrade to Gigabit Internet and just want to make sure my internal network is up to it. I have a decent wired network supplemented by a wireless network. I have 2 Synologies, a 918+ and a 215+ basically one backs up the other.
As an experiment using a File Explorer on a Windows PC I copied a 35Gb folder from one NAs to the other, the folder contained music and video files.

The two NAS and the PC are connected (upstream) to a TP-Link managed gigabit switch which is connected (upstream) to a Wireless Router (it is a cheap Chinese router but I am quite impressed by it). The cables are all Cat6 according to the lettering on the cables, they were bought from Ebay.

The folder transferred at approx 35MB/s

I set up a remote folder on one of the NAS and copied the same folder accross, this time I got 55-65 MB/s

I can live with that but I would have thought I should be doing better - but I don't know where to start investigating

FWIW, I SSH'd onto a NAS ( and did a traceroute to the other NAS ( and I got a 1 line response

xyz@DS215Plus:/$ traceroute
traceroute to (, 30 hops max, 60 byte packets
1 ( 0.111 ms 0.121 ms 0.092 ms

which I would think indicates that the route goes 'up' to the switch and 'down' to the other NAS, doesn't have to go to the router.

Any suggestions on what to look for or investigate?
In my world 60MB/S is an acceptable speed for mixed small and bigger folder copy operation between two nas devices.
One big file may copy with speeds around 100MB/s and mith many smaller files it may be much much lower, just because of latency plays a bigger role.
I just installed iPerf3 on a NAS and connecting from my PC it shows

C:\Users\xyz\Desktop\iperf-3.1.3-win64>iperf3 -c
Connecting to host, port 5201
[ 4] local port 54780 connected to port 5201
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-1.00 sec 97.9 MBytes 821 Mbits/sec
[ 4] 1.00-2.00 sec 106 MBytes 892 Mbits/sec
[ 4] 2.00-3.00 sec 107 MBytes 901 Mbits/sec
[ 4] 3.00-4.00 sec 110 MBytes 921 Mbits/sec
[ 4] 4.00-5.00 sec 110 MBytes 920 Mbits/sec
[ 4] 5.00-6.00 sec 112 MBytes 938 Mbits/sec
[ 4] 6.00-7.00 sec 109 MBytes 912 Mbits/sec
[ 4] 7.00-8.00 sec 112 MBytes 941 Mbits/sec
[ 4] 8.00-9.00 sec 112 MBytes 943 Mbits/sec
[ 4] 9.00-10.00 sec 112 MBytes 944 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 1.06 GBytes 913 Mbits/sec sender
[ 4] 0.00-10.00 sec 1.06 GBytes 913 Mbits/sec receiver

iperf Done.

Looks pretty good to me - I'm still left wondering why File Explorer is showing 35MB/s and File Station 65MB/s.

Last edited:
Iperf is cheating, It is copying just one 1GB file, without significant overhead, it is a good way to test maximum, sustained data transfer speed.
If you copy a folder, with smaller files there is all sorts of overhead in the process. Certainly if you copy via windows, that is adding another layer of overhead, so that is even slower.

if you zip your folder into one file, you will notice speeds close to the iperf result.

Internet is full of explanations for this . The smaller the files, the slower the copy.
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My take from experience.
I buy pre-ended cables for point to point connections. For room to room I use cable and punched down to jackfield.
I bought an LED Ethernet cable tester.

The EBay cables I bought passed LED Tester, yet toggled back & forth between 100 & 1000Mb speed and detection! eBay cables passed LED Tester, yet Failed!

I bought a cheapie Netgear 5 port managed switch, just for the cable test routine within it. Tested ALL cables, and found my punch down cables were good, but many of the ended cat6 cables bought from EBay cables failed with an “Impediance Missmatch”.
Ended up pitching about 16 cables overall. About 80% of all EBay cables bought. PITCHED THEM ALL!

Re-Purchased new CAT6 cables with ends from reputable dealer, and TESTED THEM before installing. This practice continues to this day.

Seeing that a professional Ethernet cable tester is 6-800$$, spending $20 for a switch for i’s cable test routine was with it’s weight in gold!!!

Unless you know for certain that your cables are good, Don’t trust any cable unless you test them first. Knowing cables are tested good is a great “Starting point”.
I learned the hard way, and lost a couple of months chasing ghosts.
My TP-Link SG108E managed switch has some sort of a cable tester, not sure how good or bad it is but it is reporting that all my current cables are 'normal' and have a link speed of '1000Full'

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