Remote Access VPN: IKE_AUTH response 1 [ N(AUTH_FAILED) ]

adsw · December 18

Hello all,

I replaced my Zyxel ZyWALL USG110 with a Zyxel USG FLEX 200H. I configured the Remote Access VPN on the new gateway and setup a IKEv2 profile on an iPhone with iOS 18.x, using the built-in VPN client. I also installed the required self-signed certificate, which I had to manually trust.

When I enable VPN on the iPhone, the IKE_SA_INIT phase is passed without errors, but the IKE_AUTH phase ends with the error message IKE_AUTH response 1 [ N(AUTH_FAILED) ]. It seems that the iOS VPN client is not sending a certificate request and so the authentication fails. With my old gateway and a profile setup under iOS 17.x, everything worked fine. The error only occurred after creating a new profile under iOS 18.x.

I sent a request to the Zyxel support about this and they told me that this seems to be a bug in iOS 18.x. I found information about aHave any of you encountered the same issue and perhaps found a solution that doesn't end in waiting for a bug fix?

Thanks, adsw

Zyxel_Kay · December 18

Hi @adsw

It appears that iOS 18 introduced changes to the VPN Phase 1 and Phase 2 parameters for its native VPN client. We recommend adjusting the Encryption and Authentication settings on your VPN configuration to align with these updates.

For step-by-step guidance, please refer to this post on our Community:

https://community.zyxel.com/en/discussion/26146/why-cant-i-establish-a-vpn-connection-after-updating-to-ios-18-how-can-i-resolve-this-issue

adsw · December 18

Hello Zyxel_Jeff,

Thanks for the tip and the links, but I have already followed resp. tried these instructions, unfortunately without success. The error message remains the same. Changing the proposals for IKE_SA_INIT (Phase 1) and IKE_AUTH (Phase 2) leads to the same error as before.

I am at a loss, because the same settings worked fine with the old gateway. The only explanation I have at the moment would be the iOS bug mentioned earlier.

Best,
adsw

Zyxel_Kay · December 19

Hi @adsw

Have you tried manually adding the IKEv2 VPN profile? This method might help resolve your issue. You can follow the step-by-step guide in this article:

How do I manually add an IKEv2 VPN profile on an iPhone for an IKEv2 VPN connection? — Zyxel Community

Let me know if this works for you!

adsw · December 19

Hello Zyxel_Kay,

Thank you for your answer.

Yes, I tried it to add the profile manually. Server and Remote ID = DDNS server, User Name, Password set and also tried to set Local ID = User Name. Certificate exported and installed and manually trusted in settings on iPhone.

Long story short. Unfortunately, it doesn't help. But thank you for the tip.

Remote Access VPN: IKE_AUTH response 1 [ N(AUTH_FAILED) ]

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