Site2Site VPN with Fritzbox

Hi,
I'm trying to set set up a site to site VPN connection with a fritzbox using swanctl, in detail via swanctl.conf.

I'm always ending up with the following when I try to test the connection:

...
[ENC] parsed IKE_SA_INIT response 0 [ N(NO_PROP) ]
[IKE] received NO_PROPOSAL_CHOSEN notify error

I can set up any protocols without any changes on the error.

Has anybody a working swanctl.conf that works with a fritzbox that can get shared here?

Thanks for your support!

What is in

ubus call system board

In general both ends should have overlapping parameters, like groups, ciphers etc.

I dont have such an access to the Fritzbox and in the overview there is nothing related to ciphers listed...

Do you run OpenWrt software on your routers?

Nope, I opnly have on my side a OpenWrt Router but on the other side a AVM Fritzbox. I'm trying something like described at https://www.mundhenk.org/fritzbox-openwrt-vpn but as the article is alread quite some days old and not using swanctl it will not work.