IPsec S2S peer IP negotiation problem at reserve ISP.

Hi.
I’m trying to connect main and branch offices by IPsec Site-to-site VPN.
In main office we have Mikrotik 1100AHx2, branch uses D-link DSR-250.

Mikrotik used as main users gateway with 2 ISP and bridge to other gateways.
I create some IPsec VPN at reserve ISP channel, but very often Mikrotik try to establish connection to remote IPsec peer by main ISP, from another IP, than set up in IPsec settings.
It causes tunnel crashing.

Can you recommend something to repair this issue?