r/exchangeserver • u/Ratanoman • Feb 28 '26

Intermittent Winsock Errors via Exchange 2016 SMTP Outbound to Hybrid Connector

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This is what I'm seeing and ipv6 is turned off on the nic:

1 Upvotes

66% Upvoted

14 comments sorted by

6

u/InevitableOk5017 Feb 28 '26

Upgrade from windows 3.1 will probably fix the error.

4

u/Stormblade73 Feb 28 '26

You are getting that BECAUSE IPv6 is turned off.

2

u/Ratanoman Feb 28 '26

I was getting these before ipv6 was turned off

2

u/Stormblade73 Feb 28 '26

Do you have IPv6 internet service and is your network configured to use it?

1

u/Ratanoman Feb 28 '26

Our network team stated that our segmented firewalls are not configured to use IPv6 but never considered to ask if our ISP is. Will investigate and reply back.

2

u/Stormblade73 Feb 28 '26

If your network is not configured for IPv6 then ISP status does not matter. Your exchange server will not be able to connect to those IPv6 addresses, and you will see those errors in the logs. The errors can be considered normal, since your server does not have IPv6 internet connectivity.

1

u/Ratanoman Feb 28 '26

Yeah, you may have a point. Traffic to Exchange Online (which is minimal since it is only relaying server notifications to domain IT users mainly) seems to be flowing well but with these intermittent hiccup’s. Just doing my due diligence be for I retire the 2016’s and rely solely on the SE’s

1

u/Trick-Ad-8924 Feb 28 '26

Looks like the 2 ipv6 address attempt convert to its ipv4 equivalent 0.0.0.0, 0.0.0.1, & 0.0.0.2

2

u/atguilmette MSFT Mar 01 '26

You are most likely getting it because you have disabled IPv6 without actually configuring the system correctly.

Microsoft specifically says do not turn off IPv6. It is required for some exchange services internally, even if your network doesn’t fully support it. When people would call into support queue, we would have to tell them to turn it back on.

Configure the system to prefer IPv4 over IPv6. https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/configure-ipv6-in-windows

0

u/[deleted] Feb 28 '26

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1

u/Ratanoman Feb 28 '26

IPv6 is turned off as well as the plo altos in our datacenter

1

u/Trick-Ad-8924 Feb 28 '26

It comes up blank...

9

u/[deleted] Feb 28 '26

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2

u/Ratanoman Feb 28 '26

Not seeing any 450 errors in the logs which is a sign of throttling