I have VPN's site to site ipsec tunnels that fall after one or two days

I've got a xg210 firewall installed in my head office with static ip address that is configured to do VPN site-to-site with ipsec protocol with 12 branch offices which all have dynamic ip addresses with a cisco rv110 as their router. Both configurations match, we are using pre-shared key as autentication type and local ID as IP address:181.xxx.xxx.xxx

The IPsec policies config in XG210 is:                                                                                                   on the cisco devices we have:

Keying method: automatic                                                                                                                IKE policy table: exchange mode:main
Authentication mode: main mode                                                                                                      SA parameters: encryption:aes128, autentication:sha-1
Compress: no                                                                                                                                   DH-group: 768 bit  SA-lifetime:120     DPD: delay:10, timeout:30
PFS: enabled(768 bit)                                                                                   
Encryption algorithm
Phase1: AES128 - SHA1  key life:120,re-key:60,margin:50                                                                   VPN policy table: SA-lifetime:120         
Phase 2: AES128 - SHA1                                                                                                                     encryption:aes128, integrity:sha-1
DPD:    Check peer after every:90,Wait for response up to:110                                                                PFS key group: DH-group 768 bit
When peer unreachable: re-initiate                                                                    
If someone knows how to keep the tunnels up im down to suggestions.
PD: We need them to stay up even without traffic.