This page is a work in progress and could be pending updates.
Firewall Settings
If Photon should be accessible from remote machines (especially through the internet), make sure your firewalls do not block connections.
Mandatory default ports are listed at this page.
To check settings, open the Windows Firewall in the Windows Control Panel. Click "Allow a program through Windows Firewall" and verify "PhotonSocketServer" is listed and checked.

You can make use of this PowerShell script to open all default ports used by Photon Server:
$fw = New-Object -ComObject hnetcfg.fwpolicy2
$ruleTcp = New-Object -ComObject HNetCfg.FWRule
$ruleUdp = New-Object -ComObject HNetCfg.FWRule
$ruleTcp.Name = "Photon SocketServer TCP"
$ruleTcp.Protocol = 6 #NET_FW_IP_PROTOCOL_TCP
$ruleTcp.LocalPorts = "80,443,843,943,4520-4522,4530-4533,4540,4541,6060-6063,9090-9093,19090-19093"
$ruleTcp.Enabled = $true
$ruleTcp.Profiles = 7 #all
$ruleTcp.Action = 1 # NET_FW_ACTION_ALLOW
$ruleUdp.Name = "Photon SocketServer UDP"
$ruleUdp.Protocol = 17 #NET_FW_IP_PROTOCOL_Udp
$ruleUdp.LocalPorts = "5055-5058,40001,27000-27003"
$ruleUdp.Enabled = $true
$ruleUdp.Profiles = 7 #all
$ruleUdp.Action = 1 # NET_FW_ACTION_ALLOW
$fw.Rules.Add($ruleTcp)
$fw.Rules.Add($ruleUdp)