My home router (Technicolor TG784n v3, firmware version 8.G.M.1) has no Quality of Service (QoS) settings. Still, I would like to implement QoS, mainly to be able to control bandwidth occupancy by CrashPlan while it's backing up files.

What happens is that when CrashPlan is uploading files it occupies a huge part of the available bandwitdh, reducing overal internet access speeds for uploading or downloading.

So here's what I have:

  • Technicolor home router acting as DHCP Server, which cannot be replaced because it is also handling IPTV and landline telephone (this router is actually connected to another router, both from my internet provider, that translates the fiber optics broadband connection).
  • Netgear WNDR3700 v2 router with DD-WRT acting basically as a switch for Gigabit LAN (the technicolor only has one Gigabit port), with DHCP forwarding to the main router.
  • Synology DS412+ NAS that also is acting as a local DNS Server (both routers are forwarding DNS requests to this server)

CrashPlan is installed on the Synology NAS and has specific QoS settings:

Advanced users only: must have QoS capable router configured. Choose the TCP Packet quality or custom DSCP value from the list: Low, Normal, Reliability, Throughput or DSCP….

I have other network devices but I guess those don't matter for this specific issue, like a Wireless Extender acting as AP and another switch in another room.

I appreciate any insight or suggestion on this, maybe using the NAS?

Thank you!


QoS is unlikely to help you & is notoriously difficult to get right anyway.

In your case, you will be better off creating some backup profiles in CrashPlan (which I also run on a Synology NAS) with each set to a suitable maximum bandwidth.

The bigger problem I have is actually that, being Java based, CrashPlan is a hog with large numbers of files to backup. On my 412+, I regularly have to stop the service if I want to use the NAS for anything else.

Unfortunately, Code42 seem unwilling to fix these issues which have been raised regularly in their forums. Whilst they are cheap, I am getting increasingly frustrated with them. In fact, I've even given up running CrashPlan on my laptop. On my previous laptop, it became such a hog that it seriously impacted performance.

  • +1. QoS markings are only valid if your network understands and acts upon them. Since the Technicolor router has no QoS settings, this is the only correct answer. – cpt_fink Apr 17 '15 at 4:37
  • Hi, thanks for your input. I actually had many issues with CrashPlan because of my very large data set until I upgraded to 2Gb of RAM. Since then it has been working very well; my backup is around 1.8Tb right now. I have tried using different profiles before and found that those actually slow down performance with such a large dataset - CrashPlan will verify the selection every now and then and that takes a lot of time. – acseven Apr 17 '15 at 9:03
  • Also, bandwidth limitation is a subpar option because available (real) upload bandwidth varies with the time of the day. I.e. I may have a 5mbps upload connection but at night that mat max out at 2mbps. This is why something like QoS would be better. – acseven Apr 17 '15 at 9:04
  • @cpt_fink Your comment actually differs from this answer, because your comment is more related to QoS implementation itself instead of CrashPlan - i.e. I recommend you to answer separately because additional comments may validate or add on that. – acseven Apr 17 '15 at 9:09
  • Interesting detail regarding CP, thanks I hadn't thought of possible issues with multiple profiles. I found I was constantly trying to trim down what was being backed up. Exceeding a million files was rather an eye-opener! Now, I'm only running CP on the NAS. Most of my PC working data is sync'd to cloud or NAS. I run a more efficient tool to backup specific settings files. – Julian Knight Apr 17 '15 at 9:18

There's a few things going on...

Crashplan on Synology NAS

I blogged about setting DSCP values for Crashplan traffic on a Synology NAS , but in short you can set the TOS or DSCP value of upload traffic using the Crashplan GUI. However, there are some serious bugs in the QoS settings available:

  • Setting 'Low' does nothing.
  • Setting 'Normal' does nothing.
  • Setting 'Reliability' gives a TOS hex value of 0x4 (equivalent to DSCP decimal value of 1).
  • Setting 'Throughput' gives a TOS hex value of 0x8 (equivalent to DSCP decimal value of 2).

Worst of all, setting your own 'DSCP decimal value' via the gui, is completely incorrect. What it actually does it set the TOS decimal value instead. So:

  • Setting a 'DSCP decimal value' of '40' will actually give you a DSCP value of 10
  • Setting a 'DSCP decimal value' of '48' will actually give you a DSCP value of 12

So, it's all pretty screwed up, but you can make it work.

These finding were using a Synology DS415play. I'm assuming you're using the package from PCLoadLetter.co.uk.


I'm not entirely clear on your setup but ultimately you need to act upon your outgoing traffic at the router. The technicolor router doesn't support QoS at all so forget about that. If you can just use the DDWRT router instead, you could set the QoS on that to de-prioritize DSCP 10 traffic (i.e. you set it to '40' in crashplan), and job done. I' don't have a DDWRT based router, but I have blogged about setting this up on a Draytek Router.

Bridge mode

If we assume you have to keep the Technicolor router connected to the WAN for some reason, you could still use the DDWRT router to perform QOS prioritization, either by putting the Technicolour router in 'bridge' or 'modem' mode (usually the same thing) and then connecting output of that to the WAN port on the DDWRT.


Double NAT

Leave the Technicolor router doing normal NAT, and connect the LAN port to the yellow WAN port of the DDWRT router, giving you a 'double NAT' situation. So long as you connect all you lan devices to the DDWRT router, you can largely forget about the Technicolor router upstream. This router can then prioritize all the traffic channelled through it to its WAN port. Its important to realise that anything left connected to the upstream Technicolor router will bypass QOS.

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