Settings parameter "weballowed" is the list of IPs that can connect, and empty list apparently means all. You can set that by editing settings.json, or via the File-Settings dialog. However, there appears to be a bug:
BUG: File-Settings dialog is overwriting/truncating the settings.json file when you click Apply. It's only writing some of the settings, (maybe just the changed ones, or just the ones on that tab?), and ignoring the rest. And it overwrites the file in place, so you see the cruft from the prior settings still there, but they're past the closing bracket so won't be read. Observed on Wallet 0.26, Linux
EDIT: Also, it seems wrong that empty list on a parameter called "weballowed" means everyone allowed. Empty should mean none allowed. Should be something like "*" or "*.*.*.*", or a broadcast/mask address to mean everyone allowed.
Keep a backup of your settings.json
Here is a standard one:
{
"knownpeers":[
],
"rpcallowed":[
"127.0.0.1"
],
"weballowed":[
"127.0.0.1"
],
"guienabled":true,
"rpcenabled":true,
"webenabled":true,
"systray":true,
"maxconnections":100,
"minconnections":10,
"generatorkeycaching":true,
"checkpoint":true,
"soundreceivepayment":true,
"soundnewtransaction":true,
"soundreceivemessage":true
}