No default gateway

[V4705]

Hi, I only have 2 LANs and 1 WAN, with 1 gateway that used to work great until I changed some settings in it (WAN IP ang Gateway IP after moving to a different ISP),
For some reason, all the Rules with default gateway doesn't work (no internet access), when I set the gateway manually on a rule it does work.

I only have 1 gateway and under routing it say default.
I tried to create another gateway and set it as default and changing the 1st one back to default (just to "reset" the setting) and it didnt work.
Also rules that I set with a manual gateway stop working after setting it back to default.

Any ideas?

Thanks!