Two hosts cannot communicate

#!/usr/bin/env python

"Setting the position of Nodes with wmediumd to calculate the interference"

import sys
from mininet.node import OVSBridge, Host,Controller,OVSKernelSwitch
from mininet.log import setLogLevel, info
from mn_wifi.link import wmediumd
from mn_wifi.cli import CLI
from mn_wifi.net import Mininet_wifi
from mn_wifi.wmediumdConnector import interference
from mininet.link import TCIntf,TCLink

def topology(args):
    "Create a network."
    net = Mininet_wifi(link=wmediumd, wmediumd_mode=interference,
                       noise_th=-91, fading_cof=3,switch=OVSKernelSwitch)

    info("*** Creating nodes\n")
    ap1 = net.addAccessPoint('ap1', ssid='new-ssid', mode='a', channel='36',
                             position='15,30,0')
    net.addStation('sta1', mac='00:00:00:00:00:02', ip='10.0.0.1/8',
                   position='10,20,0')
    net.addStation('sta2', mac='00:00:00:00:00:03', ip='10.0.0.2/8',
                   position='20,50,0')
    net.addStation('sta3', mac='00:00:00:00:00:04', ip='10.0.0.3/8',
                   position='20,60,10')
    srv1=net.addHost('server', mac='00:00:00:00:00:05', ip='10.0.0.4/8')
    s1=net.addSwitch('s1')
    net.addLink(s1,ap1)
    net.addLink(s1,srv1,cls=TCLink)
    c1 = net.addController('c1')

    info("*** Configuring Propagation Model\n")
    net.setPropagationModel(model="logDistance", exp=4)

    info("*** Configuring wifi nodes\n")
    net.configureWifiNodes()

    if '-p' not in args:
        net.plotGraph(max_x=100, max_y=100)

    info("*** Starting network\n")
    net.build()
    c1.start()
    ap1.start([c1])

    info("*** Running CLI\n")
    CLI(net)

    info("*** Stopping network\n")
    net.stop()

if __name__ == '__main__':
    setLogLevel('info')
    topology(sys.argv)
Question: When I used sta1 ping server, it doesn't work.
intrig-unicamp / mininet-wifi

Two hosts cannot communicate #460
