Please be kind and direct me to the location (and/or) procedure to change the MTU? Is it in 3Com or someplace else? I am much obliged. Kirt -----Original Message----- From: usr-tc-bounces+kbajwa=tibonline.net@mailman.xmission.com [mailto:usr-tc-bounces+kbajwa=tibonline.net@mailman.xmission.com] On Behalf Of Jason Percle Sent: Monday, July 25, 2005 1:37 PM To: 'Discussion relating to the 3Com/US Robotics Total Controlmodemsystems.' Subject: RE: [USR-TC] RE: Dial-In Problem!!!! Check your MTU size. I believe the recommended size for dialup is 576. _____ From: usr-tc-bounces+jjperc=petronet.net@mailman.xmission.com [mailto:usr-tc-bounces+jjperc=petronet.net@mailman.xmission.com] On Behalf Of Kirti S. Bajwa Sent: Monday, July 25, 2005 6:31 PM To: usr-tc@mailman.xmission.com Subject: [USR-TC] RE: Dial-In Problem!!!! Hello: Please help. This problem is going on for the last 7 weeks without fixing. TC1000 1-HiPer NMC 2-HiPerARC 10-Hiper DSP We are a small ISP (400 customers). We have 2-ISDN-PRI lines for our customers to dial in. Our entire system looks like this: / / T1 to Internet Backbone / CISCO 26XX Router | HUB 10/100 | ---------------------------------------------------------------------------- ----------------------------- | | | | | | NMC ARC1 ARC2 Web Authentication Internal Network ----------- 3Com ------------ Server email Server | | | | | | | | | | | | Customer Dial-In Our customers can dial-in, are authenticated and can access the internal web site (www.tibonline.net <http://www.tibonline.net/> ) and retrieve their email. But when they try to connect to any web site (outside our network) on the external net (such as www.yahoo.com <http://www.yahoo.com/> ), they time out with a message saying that "this page can't be displayed". We have changed the HUBs, RJ45 cables. We have the CISCO Router tested fine. Finally, I replaced the 3COM box with a backup box and the problem continues. Interestingly, we can access any Internet web site (www.msn.com <http://www.msn.com/> , www.yahoo.com <http://www.yahoo.com/> , etc.) from our internal network (over LAN) without problem. I have called Sprint, who provides us with ISDN-PRI lines. They claim that the lines are testing OK. Has anyone faced the similar problem? If YES, what was the solution? Kirti