Thanks for the fast reply.
OK thanks for clarifying about the WAN IP of the router, as I did have that as a different IP.
I still cannot ping the device (I'm actually testing with a simple PC to ensure nothing strange in the device complicates things).
Here is my network:
config interface 'loopback'
option ifname 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config globals 'globals'
option ula_prefix 'fdfa:c7ba:801d::/48'
config interface 'lan'
option ifname 'eth0.1'
option proto 'static'
option netmask '255.255.255.0'
option ip6assign '60'
option hostname 'GL-MT300N-V2-66c'
option ipaddr '192.168.100.2'
config interface 'wan'
option ifname 'eth0.2'
option proto 'static'
option netmask '255.255.255.0'
option metric '10'
option ipaddr '192.168.1.135'
config device 'wan_dev'
option name 'eth0.2'
option macaddr '94:83:c4:04:a6:6c'
config switch
option name 'switch0'
option reset '1'
option enable_vlan '1'
config switch_vlan
option device 'switch0'
option vlan '1'
option ports '1 6t'
config switch_vlan
option device 'switch0'
option vlan '2'
option ports '0 6t'
firewall:
config defaults
option input 'ACCEPT'
option output 'ACCEPT'
option forward 'ACCEPT'
config zone
option input 'ACCEPT'
option forward 'ACCEPT'
option output 'ACCEPT'
option name 'lan'
option network 'lan'
config zone
option input 'ACCEPT'
option forward 'ACCEPT'
option output 'ACCEPT'
option name 'wan'
option network 'wan'
config forwarding
option dest 'lan'
option src 'wan'
config forwarding
option dest 'wan'
option src 'lan'
config redirect
option name 'dnat_rob'
option src 'wan'
option src_dip '192.168.1.135'
option dest 'lan'
option dest_ip '192.168.100.1'
option proto 'all'
option target 'DNAT'
config redirect
option name 'snat_rob'
option src 'lan'
option src_ip '192.168.100.1'
option src_dip '192.168.1.135'
option dest 'wan'
option proto 'all'
option target 'SNAT'