Hello forum,

I have 2 server in my LAN:

- HP-ProLiant Gen8 for my office (running Ubuntu server 16.04 LTS) - connected with 4 m ethernet cable to rooter (Gigabit port)
- Odroid C2 as private media server (running Kodi/LiebreElec 8.0) - connected with 15 m ethernet cable to rooter (Gigabit port)

I have 1 client in my LAN:

- Laptop: Lenovo W520, Linux Mint 18.1 (Mate 1.16) - connected with 5 GHz Wifi to rooter (4 m distance)

I have 1 rooter in my LAN:

- TP-Link TL-WDR4300 v1, Firmware Version: OpenWrt Chaos Calmer 15.05.1/LuCI 15.05-149-g0d8bbd2 Release (git-15.363.78009-956be55), Kernel Version: 3.18.23

Sometimes I perform file transfer from my client to the servers using Linux Mint file manager (Caja) and sftp or smb protocol.
The Caja transfer manager then shows only a rate between 600 kByte/s and 1.2 MByte/s for each file, so  transferring of 1 DVD (4 GB) takes 1 - 2 hours.

For my expectations, the slowest link in the chain is the Wifi connection between laptop an rooter with 240 Mbit/s (~30 MByte/s). Regarding possible overhead and error corrections I would expect a rate rather more than 1.2 MByte/s (maybe 10 to 20 MByte/s), depending on how many files I am transferring.

Investigations already done:

Client:
- Wifi speed (according to network manager): 240 Mbit/s (~30 MByte/s).
- CPU usage during file transfer: 2 %

Server HP ProLiant
- CPU usage during file transfer: 2 %

Server Odroid C2:
- CPU usage during file transfer: 2 %

Rooter TP-Link:
- CPU usage during file transfer: 9 % (/bin/busybox top -bn1)

transfer of single file vs. multiple files:
- individual transfer rate slightly decreases from 1.2 Mb/s to ~0.7Mb/s but overall rate rises from 1.2 Mb/s to ~2.0 Mb/s, depending whether I transfer one or three files at the same time.

My questions:

Is 1.2 MByte/s the maximum rate I can expect and I have to live with this?

Or is there something wrong/misconfigurated in the transfer chain?

If so, how can I trace this?
Where/how should I start searching?
How can I understand (and report here) the information of "Realtime Graphs" in LuCI?

Thanks for tips and kind regards

Ruuter