I get a local IP 192.168.1.100 and I can use the internet but can not connect to
my second computer nerby that have the ip of 192.168.1.120.  What is wrong ?

#  /etc/config/network
#### VLAN configuration
config switch eth0
    option vlan0    "1 2 3 4 5*"
    option vlan1    "4 5"

#### Loopback configuration
config interface loopback
    option ifname    "lo"
    option proto    static
    option ipaddr    127.0.0.1
    option netmask    255.0.0.0

#### LAN configuration
config interface lan
    option type     bridge
    option ifname    "eth0.0"
    option proto    static
    option ipaddr    192.168.1.1
    option netmask    255.255.255.0

----------------------------------------------------------
Wifi
config wifi-iface
    option device   wl0
    option network    lan
    option mode     ap
    option ssid     OpenWrt

iptables
# Masquerade dynamic form of SNAT
iptables -t nat -A POSTROUTING -o eth0.1  -j MASQUERADE