SoftEther VPN User Forum

Trying this again. Works with Mac and Windows clients. Will NOT work with iOS: VPN Connection fails.

If I do not enter a password on the iPhone, a dialog pops up asking for the password, so it IS communicating with the server, but it fails authentication.

Forwarded UDP ports: 139, 443, 500, 4500

If you open UDP/139, there is a high risk of being attacked, so close it immediately.
People all over the world can see your file share.

UDP / 443 is also not used, so let's close it.

It seems that the authentication settings are incorrect.
If you don't show me your settings, I won't know the cause.

Thank you. I have closed those ports.

Here are some screen shots. iPhone is using L2TP. I have tried different encryption settings, none have worked with iOS. All work just fine with the desktops.

Since the problem occurs only on the iPhone, I think it is a setting problem on the iPhone side.
Is there a setting screen on the iPhone side?

Here's the screen. There's not much to it.

The secret must always be specified.

Both Password and Secret are filled in. Screen capture automatically blanks it out for security.

Is there any message recorded in the server log of the VPN server when the connection fails?

I just now attempted to connect with the iPhone, which failed as before. The log recorded this:

2021-01-19,19:58:26.131,SID-LOCALBRIDGE-1,-,784561C36469,FFFFFFFFFFFF,0x0800,364,DHCPv4,Request,0.0.0.0,bootpc(68),255.255.255.255,bootps(67),-,-,TransactionId=1143420210 ClientIP=0.0.0.0 YourIP=0.0.0.0 ServerIP=0.0.0.0 RelayIP=0.0.0.0,-,-,-

It seems to be part of the packet log.
There may be a record of incoming VPN connections in the server log.

I’ll check into it tomorrow and post it then. Thanks for your help.

I just attempted to connect from the iPhone again. It failed, as usual.

But there was nothing at all generated in the server log.

Does your iPhone use the same network environment as other clients that successfully connect?
Your ISP can block IPsec, so please try using WiFi to match the network conditions with other clients.

Yes. Same network and router as my desktop that’s working just fine. I’ve tried it using cellular, too.

Are the iPhone and VPN Server on different networks?
If they are on the same, you may be in a hairpin NAT state.

It is also possible that there is a problem with the DNS settings.
Can you access the VPN Server from your iPhone browser?

I am connecting to the office where the server is, from my home desktop and iPhone. So, no, they are not in the same network.

I can connect using RemotePC and other software. It is not a DNS issue.

Well, I just found the answer. iPhone does not like some non-alphanumeric characters, in this case a " (quote) in the Secret key. Changed it to a different character and voila!

One more thing to look out for!
The username must be lowercase, otherwise it will not work from iOS!
OpenVPN version v3.2.3 (3760)
IOS version: 14.6