Outlook synchronization issues over LAN network

[sharath.babu9022@gmail.com]

Hello Everyone,

Couple of locations at Japan are facing issues with Outlook synchronization (sent emails sits in outbox and no emails are received) when they are connected over LAN network but the same user's outlook is working perfectly fine when they are connected to VPN on the same PC. We have been troubleshooting this since November 11th 2018. 

We involved Cisco, Microsoft, Palo Alto and F5 but there is no clue about what is causing this issue. 

Let me explain you the setup, we have ipsec tunnel from each  location at Japan to our Data center at Singapore and these tunnels terminate on our Palo Alto Firewall, from Singapore data center we have MPLS link to our main data center at San Antonio where our F5 and Exchange CAS servers are located.

After a long troubleshooting, we finally managed to make some progress. We removed the client laptop (Japan) from the 2960 switch (WS-C2960-48PST-L) connected directly to the WAN router (Cisco 2811) and the outlook started to work. 

So there is something happening on the switch that is causing this issue.

Can anyone hep me to resolve this issue?

[balaji.bandi]

This looks for me more of Outlook not able to communicated with Exchange Server to send the emails.

on the bottom what error you see on the outlook.

couple of questions :

1. Are you able to receive the emaisl ( or you have send and receive emails).

2. is this vpn any connect or site to site vpn ?

3. what is the version of outlook and exchange server (what operating system, latest patch informtion if you can provide).

4. vpn uses different IP range, and LAN uses differe IP range, so we need to check any FW rules and capture the logs.

[sharath.babu9022@gmail.com]

Hi Balaji,



1. Are you able to receive the emails ( or you have send and receive emails). - No

2. is this vpn any connect or site to site vpn ? Outlook works fine when user is connected Cisco VPN any connect.

3. what is the version of outlook and exchange server (what operating system, latest patch information if you can provide). - It is 2010.

4. vpn uses different IP range, and LAN uses differe IP range, so we need to check any FW rules and capture the logs. - We checked the logs in the firewall, the traffic is allowed and there is no restriction.

Thank you! Please let me know if more information is needed.

[balaji.bandi]

After a long troubleshooting, we finally managed to make some progress. We removed the client laptop (Japan) from the 2960 switch (WS-C2960-48PST-L) connected directly to the WAN router (Cisco 2811) and the outlook started to work. 

can you post both the configuraiton to have look.

[sharath.babu9022@gmail.com]

Today, we change the MTU value on the dialer interface of the WAN router and it seems to have resolved the issue.

[balaji.bandi · Accepted solution]

Yes that what i have guessed, you made it clear, if this resolve mark as resolved so it will be usefull for other community members.

[sharath.babu9022@gmail.com]

Sure, will do.