Forcing site to site altime UP

Hi

I'm trying to site to site VPN to be up all the time even when there is no traffic

I went through this KB but didn't help

https://kb.fortinet.com/kb/documentLink.do?externalID=12069

What happens here is that our S2S goes down from time to time , if there is no traffic or after specific amount of time , and goes UP under two conditions:

1- If I manually bring it up.

2- If there is a traffic.

How can make it all the time up?

I'm running FGT1000D v.5.6.11

The other side is Checkpoint - not managing it and absolutely will not

And here is my p1+p2 conf:

Phase1:

    edit "My_Customer_1"
        set type static
        set interface "Cust-1-WAN"
        set ip-version 4
        set ike-version 2
        set local-gw 0.0.0.0
        set keylife 86400
        set authmethod psk
        unset authmethod-remote
        set peertype any
        set passive-mode disable
        set exchange-interface-ip disable
        set mode-cfg disable
        set proposal aes256-sha1
        set localid ''
        set localid-type auto
        set auto-negotiate enable
        set negotiate-timeout 30
        set fragmentation enable
        set dpd on-idle
        set forticlient-enforcement disable
        set comments ''
        set npu-offload enable
        set dhgrp 2
        set suite-b disable
        set eap disable
        set wizard-type custom
        set reauth disable
        set idle-timeout disable
        set ha-sync-esp-seqno enable
        set auto-discovery-sender disable
        set auto-discovery-receiver disable
        set auto-discovery-forwarder disable
        set encapsulation none
        set nattraversal enable
        set fragmentation-mtu 1200
        set childless-ike disable
        set rekey enable
        set remote-gw 1.1.1.1
        set monitor ''
        set add-gw-route disable
        set psksecret ENC
        set keepalive 10
        set dpd-retrycount 3
        set dpd-retryinterval 20
    next

phase2:

        set phase1name "My_Customer_1"
        set proposal aes128-sha1 aes256-sha1 3des-sha1 aes128-sha256 aes256-sha256 3des-sha256
        set pfs disable
        set replay disable
        set auto-negotiate enable
        set auto-discovery-sender phase1
        set auto-discovery-forwarder phase1
        set keylife-type seconds
        set encapsulation tunnel-mode
        set comments ''
        set protocol 0
        set src-addr-type subnet
        set src-port 0
        set dst-addr-type subnet
        set dst-port 0
        set keylifeseconds 43200
        set src-subnet 172.26.134.96 255.255.255.240
        set dst-subnet 172.22.0.0 255.255.0.0