Hello,
i have the same issue with >2 simultaneous VPN channels on a RUT955. Only the last VPN tunnel in the configuration list will be established automatically, all others are not working as expected. The error message is pretty similar, if i try to establish one of the other tunnels in parallel to the last one. I am using Firmware RUT9XX_R_00.05.03.3, Build Date: 2018-12-11, 07:38:19.

Single VPN channel setup works like a charm, but unfortunately i need to be able to connect to various VPN nets automatically and simultaneously.
Calling "ipsec statusall" in CLI shows the last ipsec tunnel established, a passthrough0 for local network defined and the other VPN tunnel known to the ipsec daemon.