Hello @Jonas Larsson ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you have an existing site to site VPN connection from your on-premises to Azure and you added a point to site VPN configuration on it and are able to access the Azure VMs from the VPN client but are unable to connect to your on-premises resources.
In order for you to be able to access your on-prem network (which is connected to Azure VPN by site-to-site connection) from your Point to site VPN client, your Site-to-Site VPN connection should be running BGP.
If your site-to-site connection between Azure and On-prem uses BGP, then you can just manually add the routes for your on-prem network to the Windows P2S client and will be able to access the on-prem network from your point to site connection/client. For non-windows clients, you do not need to add the manual routes as BGP is enough for the routes to be propagated.
To manually add the On-prem network route, you can browse to %AppData%\Microsoft\Network\Connections\Cm*yourGuid\routes.txt* (C:\Users\userID\AppData\Roaming\Microsoft\Network\Connections\Cm*VPNGuid\routes.txt*) in your client machine and add the route in this text file.
Kindly let us know if the above helps or you need further assistance on this issue.
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