Unable to sync on Ubuntu 16.04

[hitobb]

I start the node on ubuntu16.04 and stand for several hours, but connection can not be found.
Please give me some advice for sync?

testuser@ember: $
./Emberd getinfo
{
"version" : "v1.1.4.0-gv1.1.4.0",
"protocolversion" : 77777,
"walletversion" : 60000,
"balance" : 0.00000000,
"newmint" : 0.00000000,
"stake" : 0.00000000,
"blocks" : 0,
"timeoffset" : 0,
"moneysupply" : 0.00000000,
"connections" : 0,
"proxy" : "",
"ip" : "xxx.xxx.xxx.xxx",
"difficulty" : {
"proof-of-work" : 0.00024414,
"proof-of-stake" : 0.00024414
},
"testnet" : false,
"keypoololdest" : 1507506600,
"keypoolsize" : 101,
"paytxfee" : 0.00010000,
"mininput" : 0.00000000,
"errors" : ""
}
testuser@ember:~$

rpcuser=xxx
rpcpassword=xxx
server=1
daemon=1
port=10024
rpcport=10022
rpcallowip=*
addnode=54.209.38.230:10024
addnode=27.120.85.170:10024
addnode=173.177.158.73:10024
addnode=65.35.63.8:10024
addnode=103.53.231.85:10024
addnode=104.168.145.223:10024
addnode=104.223.72.159:10024
addnode=105.102.174.173:10024
addnode=108.61.103.22:10024

testuser@ember:$more
/etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.3 LTS"

testuser@ember:$
sudo ufw status
Status: active
To Action From
22 ALLOW Anywhere
10022 ALLOW Anywhere
10024 ALLOW Anywhere
22 (v6) ALLOW Anywhere (v6)
10022 (v6) ALLOW Anywhere (v6)
10024 (v6) ALLOW Anywhere (v6)

[hitobb]

It was solved by enabling IPv6 and adding IPv6 nodes.