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IP Change - exhcnage cannot connect

We were locked out of our old router. I got a new router, changed it's IP address and the starting DHCP pool to approximate to the previous router, and installed.

Client computers can connect to the servers SQL database fine, but when trying to connect or add the old exchange mailbox the following error comes up.

"The action cannot be completed. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

So I am in Exchange System Manager - what do i look for?

Here is another issue.....before I changed the routers IP address to be the same as the old router, the server would not even connect to the internet. It seemed to be blocked somehow - is that related?

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Phiwi Moyo
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Compare your settings on the router and the server take screen shots and post here.
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This is the breakdown of steps I took.


After installing new router/modem, it was at this point that server would not access internet, would not load IE or google home page, could not ping any external domains e.t.c

Client computers could access internet fine, BUT could not connect to exchange, network drives or SQL database on server.

CHANGED router LAN IP to (to match old router)

After this change, clients computers could connect to network drives and SQL, but not exchange.

One of the exchange mailboxes was chached for offline, and would send email OUT, but not recieve. I removed mailboxes completely, then tried to reconnect then and got the error message as shown in first post.

WAN IP has changed, because we have changed ISP. That was the reason to get a new modem/router, so we could actually update new ISP settings. But should new WAN IP explain why clients cannot connect to exchange mailbox? Does that explain why server would not even connect to internet? These are internal IP issues that external WAN IP change should not effect right?

I will get ipconfig of old router tomorrow.
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Internal Isues:

1)Exchange Net Not working
 if your router is gateway for your network then your router LAN ip should be gateway for exchange, check Exchange Gateway ip.

2) when you change router ip to old router ip share drives not working
a)your OLD ip was 192.16.0.X for your DC, have changes the IP of your DC? "please dont change"
b)if your DC, DNS having 192.16.0.x IP and your clients having 192.168.1.X ip, for sure there will be no communication.
c)check your server IP gateways and Clients gateways if DHCP is enable for clents, you may need to flush DNS entries @ client side or reboot

1)make sure your NEW router has old LAN IP (, dont change any IP or Gateway for your servers, if you are using DHCP for clients change scope to previous scop and request clients to reboot. (you may need to check dns entries in DNS if dynamic registration is enable on DHCP scope). Configure below on your new router

WAN----------------NEW WAN IP
LAN----------------- (OLD LAN IP)

2)configure routes and add NAT. try internet once you have internet go to exchange, ping router if suceed try inetrnet if fails make sure you have right network settings).
on your router configure NAT for exchange, if your require NAT, you can take help from
configure NAT for exchange on wan 1
configure OWA for exchange on wan 1
3) request new ISP to create a PTR of mail.yourdomain.com and associate with new WAN IP
4) request your Domain provider to edit mx record to new IP.



Avatar of Syed_M_Usman
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sorry i missed one question:

"But should new WAN IP explain why clients cannot connect to exchange mailbox?"

you are right, WAN ip will not effect internal connectity, but Router LAN ip affect internal connectivity.
lets say your old exchange and host A confihration was

Exchange:, GW
now after router ip change your new configration is :

Option A-
Exchange:, GW
this may be a reason Exchange internet was not working or

Option B-
Exchange:, GW
client were enable to find DNS record for exchange and thats why mailbox was not working.

in above both option exchange mailbox will not work.

The safest way is what i wrote in my last post, change your router IP to old LAN ip and dont change any thing on your servers and clients
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Okay I will try this stuff. A question about NAT.... do you mean set up a dmz? and if so which IP should go there?
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DMZ is something else and Nat is something else. you dont require DMZ for your setup, i will try to search some good article on DMZ and NAT and shall send to you.

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

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