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ANSWERED speedtest.net - unreliable results with UDP

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I recently put in a ticket for slowdown across multiple servers. This turned out not to be a problem at all with Air, but was caused by speedtest.net (the measuring tool). A step back is necessary.


I've been on AirVPN for several months, but I always used TCP until a few days ago, when I tried using UDP, hopingto get better performance. Running speedtest.net I was surprised to find my speed was terrible!


If I connected with UDP, speedtest.net behaved very erratically. At times it didn't even load. Most of the time it loaded fine, and the test started with a decent speed, but gradually slowed down to a crawl. Often it slowed down so much that it just hanged - never completing. 


If I went back to TCP, speedtest worked fine, but the speed I got were much lower - about 30-35% of my actual (ISP) speed.


Using spekeasy.net I can get reliable results both with TCP and UDP. I was pleased to realize with UDP I get close to ISP speed (25/3).


I was just wondering if anyone else found this out.

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I spoke too soon.   I just run further test with speakeasy, and got the same crappy results as before. Clearly this is an intermittent speed issue that only occurs when I'm using the UDP protocol.  I run several tests with different servers and different ports: 53, 80, 443.  This is what I know at this stage:


1. speed from ISP is very reliable: 25 down / 2.8 up (VDSL)

2. on AirVPN / UDP speed is very variable (experienced from full speed to practically zero)

3. on AirVPN / TCP speed is constant, but only ~1/3 of full speed


Can anyone help me figuring this out?

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No comments at all?  I tried connecting directly from the router (RT-N66U / Tomatousb), and get the same behaviour:

low speed but reliable connection with TCP; erratic speed and unreliable connection on UDP.


I am not really keen on using only 1/3 of my regular speed.  Any suggestions from the staff?

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Really? In this moment the top 10 clients speeds are:


Not public. de.pngAquilae 90.07 Mbit / sec 21h 10m 42s ago Not public. nl.pngLyncis 66.06 Mbit / sec 1h 3m 27s ago Not public. nl.pngCorvi 63.22 Mbit / sec 1h 20m 17s ago Not public. nl.pngOphiuchi 44.19 Mbit / sec 6d 16h 47m ago Not public. se.pngCygni 43.94 Mbit / sec 2d 5h 1m ago Not public. nl.pngCorvi 39.5 Mbit / sec 42m 45s ago Not public. ca.pngCephei 34.25 Mbit / sec 1d 4h 24m ago Not public. us.pngSirius 32.83 Mbit / sec 17h 59m 9s ago Not public. sg.pngColumbae 32.13 Mbit / sec 1d 2h 5m ago Not public. se.pngCygni 29.77 Mbit / sec 1d 12h 42m ago


Of course the likelihood that you get higher speed from a server in a datacenter than from an ISP residential line is much higher. This is due to the fact that several western countries ISPs are applying such wild and extensive overselling on residential lines that their declared "peak" bandwidth to your node can be achieved only in very particular conditions (only in short bursts, only with some allowed protocols).


Kind regards

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I regularly get above my rated 50Mbps through my ISP through various speed tests, ftp/http downloads, and torrents. Nor does this speed come in short bursts. I've tried many servers and haven't gotten above 12Mbps yet using speedtest.net or direct downloads. Yes its a residential line but the speeds are consistent. 

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Yeah, my point was really about the wildly different behaviour between TCP and UDP protocol, over my PPPoE connection to the ISP. 


I'm not able to saturate my connection using AirVPN with either protocols but, in my experience, UDP is quite a bit faster than TCP -

which is why I was looking for a solution. The difference was caused fragmentation (MTU issue), and only affected a UDP connection.


Just in case someone happens to have the same weird problem in the future.  :-) 

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