Establish s2s ikev2 vpn connection between sophos and windows server ras

Dear,

We are configuring site-to-site ikev2 vpn connection between sophos firewall and a windows server that with remote access service installed.

Now a normal PC can connect to windows server by native vpn config. But sophos failed to connect to windows server with any profile.

I tried ikev2 profile, and capturing packet on my windows server. The packets show that IKE_SA_INIT Initiator Request and Responder Response was sent back. And no more packet returned from sophos firewall.

I think it might be a reason that I cannot select user authentication in advanced settings if I use ikev2 profile on sophos firewall. And I found this discussion but the link in answer was 404.

So how to site2site connect sophos firewall with a vpn server (ras) installed windows server?

I'm looking forward to your reply.

Best Regards,

iu