"Page cannot be Displayed" on CLIENTS while using ISP's PROXY SERVER through NAT & ICS

Posted on 2003-03-14
Medium Priority
Last Modified: 2013-11-30

  Hello,   I hope I explain my situation clear enough for all to understand.

  I am running an internet cafe with 1 server and 5 clients through ethernet.  The server is a AMD Athlon 700MHZ, ASUS P5MB, 256MB RAM, 20GIGsHD, Windows 2000 Server.  The Clients are same setup except they are 500MHZ and WINDOWS XP HOME & PROFESSIONAL.  Some have Realtek 10-100 and another unidentfied branded NICs and to connect them all a LINKSYS EZXS16W 16Port Workgroup Switch.  All Clients and Server have the PROXY enabled with my GATEWAY as the PROXY IP and PORT 9877.

My internet provider is through a Broadband VSAT connection.  My VSAT Modem is a Gilat 360 and is plugged into the Server which has an additional NIC for this purpose.

To share my internet connection to the clients I have used ICS for a while and recently disabled and setup NAT.  I can access the internet from all 5 clients.

Now for my problem.....  Ocassionally I will experience a message "Page Cannot Be Displayed" on one or more of the client computers while using Internet Explorer to access any sites such as www.yahoo.com. If I try to refresh the page or retype the website I still get the message. I can try accessing the same site on another client at the same time and the page will come up.

  Now if I continue REFRESHING the page it will eventually load or if I disable the proxy and set it to direct connection on the client that was experiencing the problem the page will allways load. I figure that it has to do with a CLIENT not being able to get through to the PROXY, or the SERVER not allowing ACCESS to the PROXY because when I disable it on the CLIENTS everything is fine.  Also I can surf fine on my server computer with the PROXY enabled however their were times (about 20min) when I could not access any sites on any computers (server included) through the PROXY but could access without it.  When I phoned the ISP they said their were problems with the PROXY at that time.

  I suppose that it cannot be a fault with my ISP's PROXY server when I can access websites on some clients and not others.  I would leave the proxy off and use direct connection but their is a great reduction in speed and at certain times of the day pages would take longer than dialup to load.

I cannot seem to find a pattern on the time this would affect certain clients and whats strange to me is that sometimes everything is working fine for hours and all of a sudden pages cannot be displayed on one or two clients and it is never the same one they all experience it.  Is their a problem with NAT/ICS routing to the PROXY?  Could it be that I have configured my CLIENTS incorectly to work with NAT?

Please help!

Question by:shermanlat
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LVL 41

Expert Comment

ID: 8140164
>To share my internet connection to the clients I have used ICS for a while and recently disabled and setup NAT
why did you do this? was there a problem with ICS?
what are you using for a proxy server?

Expert Comment

ID: 8141052
I agree with Steve. ICS is great for mini-networks like yours. I have 500 PCs on my network, and i have used it for up to 200+ computers.

I now use a Cisco 1720 (1250.00$) to provide access, and firewall the outside.

ICS is easy, fast, and troubleshooting is a no-brainer.

Good luck

Author Comment

ID: 8142463
I was having the same "Page Cannot Be Displayed problem" with ICS so I tryed using NAT.  

I am using the my internet GATEWAY and PORT 9877 as the PROXY as per instructions from my ISP.  Also I have "USE HTTP 1.1" and "USE HTTP 1.1 through proxy connection" enabled.

I agree that ICS is a no brainer to setup and troubleshoot.  It works fine without the proxy but I need the proxy enabled for faster surfing for my customers.
Simple, centralized multimedia control

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LVL 41

Expert Comment

ID: 8142488
this fix is for ICS and PPPoE, but try it on one WS and see if it helps
change MTU on client
use drtcp to change the MTU settings
drtcp (free)

Author Comment

ID: 8142948

I followed the instructions at Annoyances.org

PING -f -l 1500 [MY GATEWAY IP]

I got


I change the number untill I got responses.  The number I changed my MTU is 1472.  I will try it out and let you know.  Thank you.

Author Comment

ID: 8155250
I changed the MTU on 3 out of the 5 Clients and I am still experiencing random "page cannot be displayed".  I went about 2 days with no problems and out of the blue I get the "page cannot be displayed"  problem when a customer tryed clicking on the mail link at yahoo.  I refreshed, and tryed clicking back then on the link again.  I tryed closing the browser and restarting and it worked.  However another 5 minutes of surfing and another "PCBD".

I tried reducing the MTU even further to 600 with no resolution.  I noticed when I try loading the website on another client the page will then load on the client that was experiencing the problem.  Or if I restart the browser sometimes it will come up.

Can someone tell me if their is better way to setup my network to share internet?  Would installing a proxy or using a hardware router be anymore effecient?

Sh*T I even got one while clicking the SUBMIT button just now.....
LVL 41

Accepted Solution

stevenlewis earned 1500 total points
ID: 8156206
> using a hardware router be anymore effecient?
definately using a hardware router is the way to go
it off loads the proccessing power of routing and NAT to the router, and most add a hardware firewall Lynksys and dlink make good routers that are fairly cheap (about $50 US)
I have a dlink to share my dsl, and can even forward ports (to host my own web server, ftp, etc)
I can open special ports for games, or even prevent certain machines from accessing the internet. I even have a DMZ if I want to move one machine out from behind the firewall
Mine is a d-link DI 704P
has a four port switch (you can connect a hub to it), and a dhcp server (for the LAN)

Author Comment

ID: 8161271

Thank you Steven for the advice.  I think I will try to setup a software proxy first on my server and see if that helps and then probably get a hardware router.  I will give you the credit for helping me somewhat.

Do you have an idea though why it only happens when I have the proxy enabled.  And why is it that if I go to the command prompt at the same time I am experiencing the problem and ping the website I am trying to access I get a reply but no page in the browser.

Could you also recommend me a good proxy software.

LVL 41

Expert Comment

ID: 8163736
>Do you have an idea though why it only happens when I have the proxy enabled
probably a cache setting on the proxy server
>Could you also recommend me a good proxy software
I'm not real familiar with proxy servers.
you can try analogx
there is also wingate and sygate and winproxy
but get the router, by far the best solution, then you won't need the proxy

Author Comment

ID: 8167284
I came across some info from a search engine.  Seems like quite a few people are having this problem when using IE6.0 through a web proxy.  They claim IE6 has some bugs.  I will try another browser or downgrading to 5.0


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