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Unable to accsess Exchange on a wireless VLAN


I cannot access Exchange while on a wireless VLAN on my iPhone 5S. I can access it through the Outlook app, but on the mail app it says 'Cannot authenticate account information'. The VLAN is on 172.16.1.x /16 and the exchange server is on a 192.168.10.x / 24 subnet. The router we are using is a Dell SonicWALL NSA 220. I have tried messing around with the routing table.

Thanks in advance!
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MASEE Solution Guide - Technical Dept Head
Most Valuable Expert 2017

This is something to do with your hardware which does the routing from 192.168.10.x  to 172.16.1.x.

Make sure you can reach port 443,80,25,143 from 192.168.10.x
have you added the NAT loop back rule in your NSA box?
hecgomrecNetwork Administrator

My guess is that there is nothing with the routing.

If you are able to access the server (web service that is!) by lets say webmail.domainname.com by opening a browser, you browser opens a session using the server's public IP address cause it can't find it on the actual network.

I think you should check if there is a DNS service on the LAN that identifies the exchange server with the same domain name internally and external.

If that doesn't work or they already match and records do exist then check that your phone has SSL enabled on it.

Good Luck!

What i got from this is the exchange is accessible therefor not broken but only when on the wireless LAN they can't access it.
The NSA boxes need to have a loop back NAT policy in them in order to route internal traffic to an external IP of an internal unit. <<Also don't forget the firewall rule for the loop back traffic>>
But you are right too (i think)
If the wifi LAN does not have permissions to query the domain the exchange is on
Or your wifi devices sit on "one.domain" and you are adding the exchange server as "exchange-server" without "other.domain" it will fail
hecgomrecNetwork Administrator

There are many ways to handle the WI-FI settings but if not taken in consideration all possible scenarios it will be used it for it can end up not working properly.

To better troubleshoot your issue I will recommend to tap a laptop to the problematic WIFI and open an elevated CMD and ping for your "mail.domainname.com" to see if the server is found.

If the ping works, make sure this is the mail server name you are using on your phone, remember you can't use "mail.domainname.com/owa" as your server on the phone and if you are using this on a web browser maybe this is your issue.

Your server name should use only the "root" no directory.  Then in your IIS of your Exchange you must redirect request to it to "mail.domainname.com/owa" set the redirection to only this directory so when you request for mail.domainname.com/autodiscover it won't send to owa.

Good Luck!!!


Hi Stolsie,

Sorry for late comment I've been away, funnily enough I tried this originally but there was a firewall rule denying ''VLAN < LAN w/ mailserver''. Odd, clearing this rule and double checking the routing worked great.

Cheers !

Excellent glad i help give you a nudge in the right direction :)