Hi Knight
From your description I understand that you are unable to ping default gateway from SRX CLI.
If you initiate ping from SRX CLI, then it is a host-inbound-traffic for SRX and it has to be allowed under zones.
I see that you are using vlan.1 ip-address is in same subnet of gateay.
You need to add vlan.1 interface to security zone and allow host-inbound-traffic for it.
Add below and check if it helps:
root@host# set security zones security-zone Trust interfaces vlan.1
Regards,
Raveen