Access to local server .net application via public ip address

Posted on 2011-10-21
Last Modified: 2012-05-12

(I logged a previous question some months ago which didn't get a definitive answer and now I have the same issue on a client network.)

I have setup an application on a local server (actually a win7 machine) and setup the router to allow access via public ip address. This previously stopped working when a new model router was used - a problem which was then solved by using the old router again!

Yesterday for some unknown reason, this issue has returned with no change in router or anything else we can tell for that matter. I can give clients the local server address which works fine but they now have to use 2 shortcuts to access the application depending on whether they're in the office or not - annoying to say the least.

To clarify, when accessing the application using the public ip address when connected to the local lan, browsers just seem to hang (as opposed to some sort of page not found error). This happens on various client pcs with various browsers.

Can anyone shed some light or point me in the direction of the relevant router settings to check - I can only think there's either been an automated BT firmware upgrade or a Windows update perhaps?

Question by:nigelr99
    LVL 20

    Accepted Solution

    There could be a number of things going on here. If the site answers by the local address then IIS is probably configured correctly. My guess one or all of the following are occurring

    (1) Your public IP address has changed possibly

    (2) Your ISP started blocking inbound HTTP requests for your service

    (3) Your router cannot handle clients going out of the local LAN to only come back in on the WAN interface to access the web server (which is typical)

    My suggestion would be to try and setup DNS or host files so that users only have to go to a NAME and let DNS handle if they are internal or external.

    Do you have DNS running in your environment?

    Author Comment

    Thanks brwwiggins. In response:

    1. We still access the site using the same public ip from outside the lag so it hasn't changed

    2. The site still works fine from outside the lan so I guess no blocking of any sort can be active.

    3. The router has not been changed since it was working a couple of days ago so it can't be any sort of limitation with that.

    We do not have dns running and it's an area where my knowledge fails me.. could you guide me on where to start as that sounds like the solution, regardless of the cause of the problem?

    Author Closing Comment

    OK, I finally setup 2 entries in the hosts file on each pc, the first pointing to the local lan and the second, the wan ip address. This also allows me to use an alias for the site as suggested by brwwiggins.

    Featured Post

    How to run any project with ease

    Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
    - Combine task lists, docs, spreadsheets, and chat in one
    - View and edit from mobile/offline
    - Cut down on emails

    Join & Write a Comment

    Lync server 2013 Backup Service Error ID 4049 – After File Share Migration
    #Citrix #Citrix Netscaler #HTTP Compression #Load Balance
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

    754 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    22 Experts available now in Live!

    Get 1:1 Help Now