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Forum Discussion

munnay02_288100's avatar
munnay02_288100
Icon for Nimbostratus rankNimbostratus
Sep 22, 2016

internet speed decrease after connecting VPN

i have Airtel broadband connection at my home with speed of 16 Mbps, i get almost 15.5 Mbps while using wifi on my system and phones, but if i connect system with RSA in order to connect with office ...
BIG-IP Access Policy Manager (APM)
devops
AlexBCT's avatar
AlexBCT
Icon for Cumulonimbus rankCumulonimbus
May 11, 2021

Have look if the F5 VPN is using TCP or UDP for its tunneling protocol. This is a common problem with TCP over TCP connections when working with unstable network connections such as Wifi. Basically what happens is the wifi connection looses a packet (5-25% packet drop is quite likely over wifi), after which both the tunnel TCP session, as well as the inner TCP session are trying to recover their connection, causing a bit of a snowball effect if during the recovery process another packet gets lost.

 

The solution is to enable DTLS on the F5 VPN connection; https://support.f5.com/csp/article/K54955814

This enables the outer tunnel to use UDP instead of TCP, meaning that if a packet gets lost, only one TCP session needs to recover its session, which doesn't cause the snowball effect.

 

I've seen this myself a few times where people are working over unstable connections but not notice it until they connect to a VPN and the speed dropped to 10% of their normal speed - or less. Switching to DTLS brought the speed back to roughly 90% of its normal speed.