Editing 網路服務連線測試 (section)

== Test connectivity from WAN to the remote server ==
<span style="color:red">WAN &#9679; -------&gt; &#9679; LAN -------&gt; &#9679; server</span>

We met the trouble on WAN (wide area network). If we do no have the administrative permission, the tests we can do as follows:
*  [http://downforeveryoneorjustme.com/ Down for everyone or just me?] more on [[Web_Ping#同時從世界各處測試網站連線 | Web Ping]]
* Switch to different ISP? Is hardware firewall enabled?
* Is gateway alive?
* Is DNS alive?
* Is the external IP correct? 
** If the firewall rule is IP specified, verify the IP if correct from [http://whatismyipaddress.com/ What Is My IP Address?] or web access log.
** Query the [http://ipinfo.io/ IP Address Details - ipinfo.io]. e.g. Input the command {{kbd | key = <nowiki>curl ipinfo.io/ip</nowiki>}}<ref>[https://askubuntu.com/questions/95910/command-for-determining-my-public-ip#comment1318649_95910 networking - Command for determining my public IP? - Ask Ubuntu]</ref> for {{Mac}} & {{Linux}}
* Is the port was opened for external users? [http://www.portchecktool.com/ Open Port Check Tool - Port Forwarding Port Check Tool]
* Is institutional/ISP firewall enabled? Contact your MIS. ([https://en.wikipedia.org/wiki/Management_information_system Management information system]) of your company or ISP?

other issue: 
* bandwidth cost too much by certain users
* exceed the request limit of (hardware) firewall
* the external connection of updated Windows was down until reboot {{Win}}
* Amazon EC2 security group
* refresh browser cache: [http://refreshyourcache.com/en/cache/ Refresh your cache - When hitting F5 just isn't enough!]