RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Only to try and understand the whole stuff:

  1. the router has a DHCP client on ether1 (WAN) connected to the ISP:
/ip dhcp-client
add interface=ether1

the ISP assigns via DHCP to the ether1 an IP address and a gateway

  1. the main route points to ether1 as gateway
/ip route
add disabled=no distance=1 dst-address=0.0.0.0/32 gateway=ether1 pref-src="" \
    routing-table=main scope=30 suppress-hw-offload=no target-scope=10
  1. for some reasons when the ISP changes the IP address of the gateway, the change is not reflected on the route and/or on the ether1 inteface that keeps using the previous gateway address

  2. the script checks that the “current” gateway provided by the ISP is used in the main route

  3. after the script has been run the route will not have anymore:
    gateway=ether1
    but rather
    gateway=w.x.y.z
    where w.x.y.z is the IP address of the gateway retrieved by the:

/ip dhcp-client get $"gateway-address"

The script is a better implementation (checking that the current gateway is not already there) of the script talked about here:
http://forum.mikrotik.com/t/completing-a-script-for-checking-and-updating-dynamic-isps-gateway/147715/1

Do I get all this correctly?

Is the issue caused by incorrect ISP actions/ISP DHCP Server or by Mikrotik DHCP client implementation?