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Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

inicholson
Newbie
Posts: 4
Registered: ‎24-07-2015

Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

I've noticed that whenever I'm uploading any files (so when I start my laptop and it uploads new files to Onedrive or new music to Google Play) that my download speed grinds almost to a halt.
I can set Google Music manager to limit the upload speed (to 128kbps) but it takes forever to sync my music and Onedrive is almost useless.

Is there a way to resolve this or is it just a fault with with Plusnet routers/Plusnet/ADSL?

4 REPLIES
Community Gaffer
Community Gaffer
Posts: 17,678
Thanks: 664
Fixes: 166
Registered: ‎05-04-2007

Re: Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

This is mainly due to the TCP protocol and how it receives/transmits ACK packets. While you're saturating the upload with a single type of traffic, the ACK packets for anything else on your download cannot be sent at the same time, this has the knock-on effect of slowing down downloads until the ACKs are received.

If this post resolved your issue please click the 'This fixed my problem' button
 Chris Parr
 Plusnet Staff
Community Veteran
Posts: 489
Thanks: 39
Fixes: 2
Registered: ‎26-09-2015

Re: Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

While what Chris says is completely correct, the issue is made much worse if you have a router that does a lot of buffering in these circumstances, the so-called "buffer bloat".  The Plusnet 2704N is particularly bad in this respect.

inicholson
Newbie
Posts: 4
Registered: ‎24-07-2015

Re: Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

So replacing the router with something better (its range isn't that great anyway) might improve things?

Community Veteran
Posts: 489
Thanks: 39
Fixes: 2
Registered: ‎26-09-2015

Re: Uploading (syncing Onedrive or Google Music) slows download to unusable speeds

Yes it would.  Maybe not a complete solution because depending on your broadband the upload direction is really easy to saturate.  However this is one of these situations where buffering is harmful and actually slows down the transfer more than discards would do.   As they say about some protocols "better never than late".   I think the ideal would be a router that would let you prioritise small packets in the upload direction, that could cover both the TCP ACKs that cause your particular issue, and would also protect voice for example.

To check your router, run a continuous ping to ntp.plus.net (ping -t ntp.plus.net) while you run a speed test.  See what the ping time goes to during the upload part.   FYI mine shows a max of around 280ms.