I own a ER605 v1 router and want to set it to work as a VPN server so that I can connect my mobile devices to my home network if I'm away from home.
I do not only want to access my home network but also want to route my internet traffic through my router at home so that it seems my device is at home. However I haven't got that to work.

What I currently have is the following IPSec Policy:

For obvious reasons some fields show errors ;). Btw the Primary DNS server seems to disappear after navigation to another page and getting back here. I've set it to 1.1.1.1.

The IP Address Pool for the policy is a different range than my home network..

It is set to use IKEv2 with the correct settings (not sure about Phase 2 on which the Encapsulation Mode is set to Tunnel mode).

So far so good. I now can connect with my Android phone and I can access network resources. What I cannot do is access the internet (through the VPN) on my phone.

I was figuring that there is no known route for the IP range of the VPN to go to the internet so I added the following IP Address:

and then the following IP Group:

Now under Routing -> Policy Routing I added a rule:

I was hoping this would work but unfortunately it doesn't.

I do not want to use PPTP, L2TP or OpenVPN (old or slower). Wireguard would be an option but that doens't seem to be available on V1 devices.

Any idea on how to get this working?

Additional info:
The ER605 sits behind my ISP router. I port-forwarded port 500 UDP and 4500 UDP to the ER605.