If your Wallet does not sync, check:

1. if there is a newer Version on Github or the Project Website available!
2. Close the Wallet, delete the peers.dat file in your Coins ApplicationData Directory, restart the Wallet. The Wallet should now fetch the Seednodes.
3. If all does not Help, check the offical Support Channels and search for addnodes; add these to your coin-Configuration File and restart your Wallet! e.g xuma.conf:

   addnode=118.190.204.89:19777
   addnode=140.82.35.189:19777
   addnode=155.94.227.42:19777
   addnode=172.241.166.115:19777
   addnode=185.154.12.183:19777
   addnode=192.210.166.50:19777
   addnode=194.182.80.175:19777
   addnode=212.237.29.88:19777
   addnode=217.182.173.104:19777
   addnode=23.94.166.79:19777
   addnode=38.103.14.34:19777
   addnode=47.104.92.28:19777
   addnode=54.36.172.184:19777
   addnode=80.211.92.142:19777
   addnode=93.178.98.224:19777
   addnode=93.186.253.211:19777

   Hint: the Port (=Value after IP-Adress and ":") varies from Coin to Coin. Xuma has 19777, UCC has 41112, ...

Your Wallet should now sync!