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TCP vs UDP - AirVPN via NetGear R6300v1 running July 2018 DD-WRT

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Hi, I'm trying to use a NetGear R6300v1 as a VPN Router with the latest DD-WRT build I could find (dd-wrt.v24-36330_NEWD-2_K3.x_mega-R6300).

I can establish a TCP/443 connection to AirVPN (using DE or NL servers) and everything is fine in my opinion:
There seem to be no DNS leaks and when the VPN goes down the R6300v1 stops traffic over the WAN interface, just as I want it to.

With my 100/40 MBit/s NetCologne DSL @ home I see about 15/13 MBit/s VPN Performance on the R6300v1 with TCP, I have not yet seen more than 30% CPU usage on the R6300v1 during Speedtests.
Streaming 1080p YouTube videos in a browser window on a PC connected via LAN to the R6300v1 the CPU usage stays below 15%.
Streaming 4K video to an iPad connected via 5 GHz WLAN results in 25% to 35% CPU usage on the R6300v1.

This is using a TCP connection - I wonder if UDP would give me more performance and if I should strive further to get that up and running?

My problem is: With the very same settings - AFAIK I don't have anything TCP exclusive in there - just switching to UDP for connecting to AirVPN I cannot browse anything anymore.

DNS resolution still works with UDP, I can ping for example www.heise.de both in Windows and via SSH directly on the R6300v1, I just cannot browse to www.heise.de.

On a sidenote, the same is true if I use 'OpenVPN connect' on an iPad (iOS 11.4.1) - when I generate a .ovpn config for TCP/443 to German servers all is well, same config just with UDP/443 not so much on the iPad, too.

On a second sidenote, I can get the latest Tomato build I could find for the R6300v1 (tomato-Netgear-R6300V1_RT-AC6x--140-AIO-64K) to do the same and have the same UDP issue as with the DD-WRT load ... I settled for DD-WRT for now because it seems to me the hardware support, especially WLAN AC, is better in the more recent DD-WRT build I'm using.

I think I'm either missing something obvious or UDP simply cannot work on the R6300v1 (and an iPad).

If anybody has an idea what I should try differently with the settings, I'd very much appreciate the information.

Thanks in advance,

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For my first test with iPads I used an iPad Air dated back to 2013. I've been curious if a more recent iPad, also running iOS 11.4.1, would behave differently in any way regarding TCP vs UDP for connecting to de.vpn.airdns.org.


So, using an iPad Pro from 2017 I repeated my test - the Pro can connect to DE servers using UDP, just as the older Air, but it cannot browse anything with UDP.


TCP works right away on the Pro, just as it does on the Air.


The A10X CPU used in the Pro sure does perform way better for 'OpenVPN connect' than the older A7 in the Air - performing almost at line speed for the NetCologne DSL connection - see attachment.

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This is using a TCP connection - I wonder if UDP would give me more performance and if I should strive further to get that up and running?

I would say Stick to TCP. UDP only gonna give you headaches not a better performance. but that is my opinion.



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Fix, Staff - Thanks for your replies.


This article - https://airvpn.org/faq/udp_vs_tcp/ - is among the information I came accross which left me wondering if  going for UDP would be worthwhile.

It says: "<snip> On the other hand, UDP is more efficient once the connection is established.

If you experience problems with VoIP video/audio conversations when connected to the VPN through a TCP port, a typical case for which a difference may be visible (VoIP over TCP - for example UDP over TCP -  is clearly inferior to VoIP over UDP because TCP implements ARQ, UDP does not), then go for an UDP connection. <snip>"


To me that implies that UDP is somewhat superior. Since the CPU used in the NetGear R6300v1 is not the fastest, "more efficient" sounds good. And since I can establish the UDP connection with DNS availaible I'd like to give it a try if it wasn't for the "cannot browse annything issue.


Kind Regards,


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