ADSL incoming connection issue

[Belix]

Hi folks
Got something I need to resolve and not sure where the issue lies
Our server is connected to the net via and netgear GT834 v4 modem.
Every once in a while, not fixed, but about once a week somethng happens to the connections as we no longer get outside mail, and the blackberries can no longer connect to our BES server - we can however still access the internet, MSN etc...

Switching off the router, leaving it for a few minutes and powering it on again restores the full connection. I've tried a replacement modem just to illiminate it, but the new GT834 would not enable the full connection, just the local interent (ie no outside mail, no blackberry connection).

What am I missing here?? It's driving me nutty.

ADSL is 4mbps, ISP is IS uncapped.

 

[Pada]

My guess is that your ADSL modem can't handle the amount of connections.

Perhaps you should try and put the modem in bridge mode and then dial the PPPoE connection from your firewall PC/device. If you don't have a firewall PC/device, then you should get one.

Alternatively, replace the ADSL modem with an enterprise class one, instead of using Netgear ****.

 

[Belix]

Thought it only made one connection? If it makes more than one connection, that could be the problem as the IS account only allows one connection at a time...but theyn why does it work for a week.
Can you suggest a good adsl router then? Is there anything aside from the modem it could be? Would line noise or something perhaps be an issue?

 

[Pada]

Yes, the ADSL modem only makes 1 PPPoE connection to your ISP, but then it can accept/make multiple TCP/IP connections (or using other protocols) over that single PPPoE connection.
This is why I'm suggesting that you put the modem in bridge mode, and then dialing the PPPoE connection to your ISP from a PC or other firewall device that can handle many simultaneous TCP/IP connections.

I doubt that it could be a line noise issue, because then the outgoing traffic would've been affected too. It's always a good idea to double-check your line attenuation, SNR margins and sync speeds to make sure that it isn't causing other issues.

We are using a D-Link DSL-2500U ADSL modem, instead of the Cisco ADSL modem due to SNR margin issues that we had with the Cisco. I'm not sure if the D-Link is suited for a business, because we're dialing the PPPoE & L2TP VPN connections from our MikroTik RB1100 router and not from the D-Link modem.
I usually suggest the D-Link DSL-2500U and TP-Link W8960N ADSL modems for personal use, but I don't want to suggest something for enterprise use when it can't handle as many connections as a company would need!

IMPORTANT THING:
One thing which I previously didn't think of was whether you guys have a static IP address or not? If you don't have a static IP address, how have you configured your connection to accept incoming connections like for the BlackBerry server, etc.
Your situation really seems like a case where your ADSL's IP address changed, and then the DNS entry doesn't get updated, which results in all the incoming connections to fail.

 

[elf_lord_ZC5]

If you guys are not mucking around with the firewall, is it not your Dynamic DNS provider having problems, or your router not updating your IP if as and when it changes?