Android VPN doesn't work after changed server but with same settings

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onefromtheweb
Posts: 4
Joined: Fri Oct 18, 2019 6:41 am

Android VPN doesn't work after changed server but with same settings

Post by onefromtheweb » Fri Oct 18, 2019 7:13 am

Hi I'm new and never join a forum in my life so... hope not to break any rules....
Recently I've changed my server hardware and installed OS from zero (Windows Server 2019). I've re-installed VPN server and server manager and I've copied every settings (even the same static IP in LAN) of the previous server in fact everything work correctly on the server. I've tried to connect to VPN from several external networks through SoftEther client and without changing anything everything work correctly (on my notebook).
The problem comes when I tried to do the same thing with my Android Phone. With the previous server everything worked so well... with this new... it's really weird. Usually it doesn't work but I remember that a day it correctly work without problem (obviously without change anything and connecting from the same network that previous and later days doesn't work (meanwhile on notebook works). So I'm asking why... because from Notebook everything works while from phone it worked until this unsignificant change....
I've got only one HUB in fact from Android I never specified it through @ (but to try if this could work I've tried also this after problem appeared)
A bit of data:
-My notebook has Windows 10 Pro 1809, I use SoftEther client build 9696
-My android phone is One Plus A6003 with Android 9 and I use the system VPN connection manager (I've removed root long times ago so I can't use the android client). I've also tried to set DNS IP with my router and correctly set every parameter (even because before this change everything worked perfectly....)
-VPN server version is the same on old and new server and the last available on the web

onefromtheweb
Posts: 4
Joined: Fri Oct 18, 2019 6:41 am

Re: Android VPN doesn't work after changed server but with same settings

Post by onefromtheweb » Mon Apr 13, 2020 6:31 pm

up!

Now I have Android 10 on my phone and if I connect to server static local IP while I'm connected to the same entwork it works!!!! But if I am on another wifi, on 4G or simply put public IP or DDNS it doesn't work....
Just to be clear, what I've done:
-alredy open port on my router and on my server (and also tried to disable firewall on server and router but still not work)
-tried all possible option in the server manager except for EtherIP function because it's useless for me
-created a bridge with my eth card (the eth card works perfectly) (even because on my notebook work so idk)

centeredki69
Posts: 305
Joined: Wed Sep 18, 2013 1:49 pm

Re: Android VPN doesn't work after changed server but with same settings

Post by centeredki69 » Mon Apr 13, 2020 8:30 pm

What VPN protocol are you trying to use on the Android device. L2TP/IPSEC or OpenVPN?

Did you just open the ports on the router? Or did you forward the ports to the LOCAL IP address of the SE-Server HOST (win server 2019)?
For L2TP/IPsec forward ports UDP 500 & 4500 to LOCAL IP address of the SE-Server HOST (win server 2019)

OliverTejada
Posts: 46
Joined: Mon Apr 13, 2020 8:08 pm

Re: Android VPN doesn't work after changed server but with same settings

Post by OliverTejada » Mon Apr 13, 2020 8:52 pm

Remember, when connecting from an Android device, L2TP IPsec PSK is to be selected as the VPN type to connect. Make sure the feature is enabled on server, of course (I assume it already is).

-This type of VPN uses UDP negotiation, and uses ports 500 and 4500. Double check the port forwarding at your router,
- Double check the pre-shared key (NOT to be confused with shared secret, leave that empty).
- Also, username and password, double check these things to avoid failed authentication attempts.


If you're still having unsucessful attempts from that specific android device, try dialing your VPN server from another android device just to make sure. I've struggled before with some Android devices failing to connect with IPSec VPNs, due to having custom kernels, or custom roms with broken built-in VPN clients.

onefromtheweb
Posts: 4
Joined: Fri Oct 18, 2019 6:41 am

Re: Android VPN doesn't work after changed server but with same settings

Post by onefromtheweb » Tue Apr 14, 2020 10:32 pm

centeredki69 wrote:
Mon Apr 13, 2020 8:30 pm
What VPN protocol are you trying to use on the Android device. L2TP/IPSEC or OpenVPN?

Did you just open the ports on the router? Or did you forward the ports to the LOCAL IP address of the SE-Server HOST (win server 2019)?
For L2TP/IPsec forward ports UDP 500 & 4500 to LOCAL IP address of the SE-Server HOST (win server 2019)
Done both and I use L2TP/IPSEC

onefromtheweb
Posts: 4
Joined: Fri Oct 18, 2019 6:41 am

Re: Android VPN doesn't work after changed server but with same settings

Post by onefromtheweb » Tue Apr 14, 2020 10:36 pm

OliverTejada wrote:
Mon Apr 13, 2020 8:52 pm
Remember, when connecting from an Android device, L2TP IPsec PSK is to be selected as the VPN type to connect. Make sure the feature is enabled on server, of course (I assume it already is).

-This type of VPN uses UDP negotiation, and uses ports 500 and 4500. Double check the port forwarding at your router,
- Double check the pre-shared key (NOT to be confused with shared secret, leave that empty).
- Also, username and password, double check these things to avoid failed authentication attempts.


If you're still having unsucessful attempts from that specific android device, try dialing your VPN server from another android device just to make sure. I've struggled before with some Android devices failing to connect with IPSec VPNs, due to having custom kernels, or custom roms with broken built-in VPN clients.
Well, when I connect my phone to the same network of the server, set its static local IP as the server address on the phone and try to connect everything works fine so I assume that L2TP IPsec PSK is enabled... but are you talking about Softether server or a roles of Windows Server? Because I haven't found a role with this name but I could double ceck

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