you need to run a node so the wallet knows where to grab all datainformation. firewall issues is not a common error and may happends if you got alot going on(you probably already know how to fix it if you got that problem). i have not tried the light-wallet yet but the blockchain is not big(in size) so i recommend you to run a full-node.
Syncing procedure takes a lot of time for someone who start syncing their wallets for the first time.
Next syncing times will be faster than the first one.