Network-related or instance-specific error

SQLServerCentral is supported by Red Gate Software Ltd.

Popular Topics

Home

Members

Calendar

Who's On

Home » SQL Server 2005 » Administering » Network-related or instance-specific error -...

Network-related or instance-specific error - Connection Medium Problem

Rate Topic

Display Mode

Topic Options

Author

Message

ian-1024253

Posted Thursday, November 19, 2009 6:33 AM

Forum Newbie

Group: General Forum Members
Last Login: Sunday, November 22, 2009 10:21 PM
Points: 4, Visits: 17

Hi guys, I know there's hundreds of topic about this error out there, but not a single one seems to apply to my specific situation.

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

We have three branches, 1 head office and two satellite branches. Our in-house developed application connects to a SQL Server 2005 instance running on a server with a live IP which the branches connect through and a local IP that the head office connects through i.e. app at branches connect through <live IP>\<instance name> and the head office connects through <local IP>\<instance name>. The application is exactly the same across all three branches except for the connection string used...it's exactly the same for both satellite branches though.

Head office has no problems connecting with the application. Branch A has no problems either. Branch B however does. Branch B's network is setup as follows...ADSL connection into a wireless/wired router that each user then gets internet access through. If anyone in Branch B connects to the internet through 3G or their cellphones on their PCs, then the application works. But not through the ADSL setup. However, to make it more interesting...one of the guys made an initial connection to the internet using his cellphone as the modem and successfully logged into the application...he then disconnected the internet from his cellphone and connected through a cable connection to the ADSL router and successfully managed to carry on utilising the application, performing actions that would have performed SQL queries to the server...and all ran successfully. But then he closed the app and opened it again (cable to router connection) and again login failed.

Please any ideas.

Post #821548

Lynn Pettis

Posted Thursday, November 19, 2009 9:20 PM

SSC-Insane

Group: General Forum Members
Last Login: Today @ 2:36 AM
Points: 21,588, Visits: 27,374

A network person I am not, however, this looks like a netwrok issue. Please remember, I consider everything from the network card in the desktop to the network card in the server part of the network. This includes the network cards and their drivers, and the IP stack of the OS.

If both branch offices use the same hardware, I would start by comparing the setups of the both.

Cool

Lynn Pettis

For better assistance in answering your questions, click here
For tips to get better help with Performance Problems, click here
For Running Totals and its variations, click here or when working with partitioned tables
For more about Tally Tables, click here
For more about Cross Tabs and Pivots, click here and here
Managing Transaction Logs

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #822075

Steve Jones - SSC Editor

Posted Thursday, November 19, 2009 9:45 PM

SSC-Dedicated

Group: Administrators
Last Login: Yesterday @ 1:47 PM
Points: 31,406, Visits: 13,722

It definitely sounds like a networking issues between the branches. I'd double check the IP / network setup in all locations and be sure you don't have conflicts somewhere.

Also, I'd move away from IP to an FQDN. Then you can manage things with a single connection string and DNS name. Local settings can be made in the router or even client machine to override the settings for the IPs.

Follow me on Twitter: @way0utwest

Forum Etiquette: How to post data/code on a forum to get the best help

Post #822081

SQLRNNR

Posted Thursday, November 19, 2009 10:38 PM

SSCoach

Group: General Forum Members
Last Login: 2 days ago @ 1:46 PM
Points: 18,732, Visits: 12,329

Yes networking issue. It really seems like it could be routing table or dns related. You will need to check your routers, dns and adsl setup.

Jason AKA CirqueDeSQLeil
I have given a name to my pain...
MCM SQL Server 2008

SQL RNNR

Posting Performance Based Questions - Gail Shaw
Posting Data Etiquette - Jeff Moden
Hidden RBAR - Jeff Moden
VLFs and the Tran Log - Kimberly Tripp

Post #822102

ian-1024253

Posted Friday, November 20, 2009 6:55 AM

Forum Newbie

Group: General Forum Members
Last Login: Sunday, November 22, 2009 10:21 PM
Points: 4, Visits: 17

Thanks for the replies so far.

Compared setups etc, and everything checks out. Apart from one really interesting anomaly.

Company (A) which has no problems. When I try a tracert to the server IP it times out continuously. It pings the server IP however

Company (B) Which has the problems runs a succesful tracert and ping to the IP, yet they cannot connect.

What I cannot get my head around is that when someone connects via a 3G modem it logs him in fine, and then without closing the app, disconnects the 3G and connects back onto the network and then continues to use the app successfully. So it seems the only problem is during authentication. Does the logon procedure run on a different port than the default 1433? Or does something special happen during authentication?

Post #822350

Lynn Pettis

Posted Friday, November 20, 2009 7:18 AM

SSC-Insane

Group: General Forum Members
Last Login: Today @ 2:36 AM
Points: 21,588, Visits: 27,374

If you are using a named instance, you probably aren't connecting to port 1433. You may want to check the firewalls on the client sides as well.

Cool

Lynn Pettis

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #822375

Steve Jones - SSC Editor

Posted Friday, November 20, 2009 8:29 AM

SSC-Dedicated

Group: Administrators
Last Login: Yesterday @ 1:47 PM
Points: 31,406, Visits: 13,722

Good note, Ian and Lynn.

If I remember this, for a named instance, you'll connect with UDP 1434 and get the port that the instance is using, then you connect on TCP xxx

Follow me on Twitter: @way0utwest

Forum Etiquette: How to post data/code on a forum to get the best help

Post #822450

« Prev Topic | Next Topic »

Permissions