Dropbox upload slows internet speed drastically

Question

I just added a folder with some pictures and videos (~80 MB) to my Dropbox folder. Dropbox started syncing, and the "speed for browsing" dropped to unusable (DNS resolving pretty slow, websites loaded very slow or not loaded at all).

So I ran tracert to a couple of hosts and while Dropbox was syncing the reply time was between 2500ms and 3500ms or the hosts were unreachable. When I paused the Dropbox sync, the reply time almost immediately dropped to the usual 50-100ms.

Auto-limiting the Dropbox upload "improved" the reply times of tracert to 1500ms, but browsing was still painful.

I didn't experience this behavior in the past (or I didn't correlate slow internet to Dropbox sync), however I recently replaced my old Fritzbox 7170 router with a new Fritzbox 3370 (which should have at least much faster WiFi).

Any suggestions, which settings I should check?

I use cable (Kabel BW, Germany) for internet with 10Mbps download rate.

Solution

So I limited the Dropbox upload (as mentioned auto-limiting did not help) and now browsing is possible again.

I still wonder why this didn't happen in the past, maybe earlier versions of the Dropbox client (currently I'm using 2.5) limited the upload better.

Comments

[Simon]

I know that Dropbox upload is much slower than download, because of much smaller bandwidth for upload of my internet connection. But my problem is not the slow upload of Dropbox, but the Dropbox sync completely blocking my internet connection.

[Dave]

Does this issue occur on wireless and on wired connections?

[Simon]

It's a WiFi connection

[Dave]

Are you able to test it with a wired connection? The obvious issue appears to be the router; maybe you have a QoS set up (or it is automatically set up by default)

[Dave]

did you try limited the download speed to see if this resolves the issue? Again, to show the same link, take a look at the highest scoring answer. superuser.com/questions/267375/…

[Simon]

Will try today.

[Peter]

Same problem here. Other applications can happily upload at 100% bandwidth if I set them to low priority in the browser. However, when dropbox runs (which should upload at 75% of the bandwidth), browsing crawls. Fritzbox shows 100% traffic at real-time priority, even though I have no applications set to real time priority.