ZTNA agent based access in office

Hi everybody,

I would like to get some help with ZTNA in office.

I have a client with ZTNA agent installed. Accessing on prem resources over an external network works correctly.

But if I put the client into the on prem (our internal) network, access stops working.

Checking wireshark on the client I can see that it wants to connect to the resource by using source IP 100.64.0.1 destination IP 100.64.0.10. But 100.64.0.10 does not answer while in the internal network.

Am I missing something in my firewall configuration?

Edit: Maybe I should also mention that I have setup a ZTNA Gateway as VM in our internal network in Sphos Cloud Mode.

Regards

Philipp