Wireless Certificate Issues

I was wondering if anyone mayt be able to provide some insight into an issue I am experiencing at the moment. We have certificate based wifi setup, but several users are having consistent issues with connecting. The issue seems to be the certificate, as when you try to connect to the wireless this will state that the certificate for the network cannot be found on this computer.

The certificate is locally on the computer within Personal > Certificates, there is also a valid cert for the local machine in the same location. The certificate is used for VPN also and this works fine, so that seems to indicate that the certificate isn't the issue. If I generate a new certificate for the user, this will work for a number of days and then revert back to the above error.

When looking in to this, I can see when a successful connection is made, the WLAN-AutoConfig event log shows the below fields;

Identity: [firstname.lastname@domain.com](mailto:firstname.lastname@domain.com)

User: Domain

Domain: Domain

When the connection is failing it shows;

Identity: NULL

User: [firstname.lastname@domain.com](mailto:firstname.lastname@domain.com)

From the auth exchange it states the client is failing to respond with their identity, and then is timing out. As far as I know the above information is taken from the certificate locally on the machine. Does anyone have any ideas why the identity field is being presented as NULL after a period of time?

Apologies if this isn't the correct sub reddit, mods delete if needed.