My local ISP gives 2 MBPS speed for first 500 MB data. After that speed becomes restricted to 64 KBPS.
I have a custom made Android TCP VPN ( TUN Based ) for Android ( Server Linux Centos)
After speed limit is reached My VPN becomes very slow I can not see youtube without Buffering. But I have tried few TCP VPNs for Android Out of those two VPNs considerably fast, even after speed limit reached. I can see youtube properly.
I have investigated. Out of two VPNs, one VPN use double TCP connections to server and split traffic and send it via 2 different TCP connections which may make it fast if ISP limiting speed per TCP connection basis.
But another VPN still using Single TCP connection like My VPN..But still it is fast.
1. Please give me some idea about .how ISP limiting speed In this case and how to get maximum possible speed as other two VPNs doing. In MY VPN Encryption is implemented so ISP can not see data like other two VPNs.
My ISP limiting speed per IP basis?.or It is limiting speed per TCP connection . Do I need to modify MTU size, TCP window scaling, send receive buffer size or anything in TCP settings both in Linux server kernel and Android client. Because that VPN which using Single TCP connection also working properly with good speed.
I mean when Speed restricted to 64 KBPS...Those 2 VPNs can achieve 40-50 KBPS which is okay for Youtube non HD movie
Where as My VPN giving only 5- 10 KBPS. But at full speed My VPN is good like other VPNs. What I am missing in My VPN or server TCP settings.
2. Also please tell me when I set TUN MTU value 1450 or 1500 both in server and client ...My TCP VPN working fine. But if I reduce MTU to 1350 or 1370 ...It becomes very slow even at full internet speed. Browsing, youtube all are very slow. As I thought decreasing MTU does not harm. What could be the reason? Surprisingly in few mobiles MTU 1450 ,1500 working fine but MTU 1350 1300 etc..gives very slow speed. For few other mobiles things completely different, there MTU 1350 working very good but MTU 1500 giving very slow speed. All testes are done in same mobile netwrok. How to trouble shoot the issue
Can you please focus some light.
Thank you pap
For second question, when you downgrade of MTU value, more ip packet is created. More IP packet means more headers and it will downgrade the server performance. You should always use maximum MTU value and for etherenet it is 1500 byte.