Suddenly can't access Exchange Server

Hoping someone may have an idea.

My exchange server has been working fine for years and tonight suddenly it will not respond to anything. If i login locally the OWA works fine but remotely nothing.
This to me is pointing at port 443 being blocked for some reason. Exchange and IIS are working fine otherwise I would not be able to login locally on the machine.
I turned off the firewall and it did not help. Tried to turn off defender but almost impossible of server 2016.
Setup is Exchange Server 2016 running on Server 2016 under ESXi on a big HP server.
Port 443 is listening on the exchange server according to netstat.

My next thought is to restore from a backup two weeks ago and see what that does. I will lose some mail but it might start working again.
Only latest things done was a Defender update and a couple of updates from MS two days ago. It was still working after that though.

Try connecting Via IP not name does that work?

bro67 said:

Is this on a home network? Do you have a static or dynamic IP? Do you have a paid domain to allow you to connect without an IP?

How do you connect without an IP??? The server is on a home network behind a dynamic IP. My firewall routes all traffic to port 443 to the correct PC on my local network. As I said setup has been working for years.

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Samuria said:

Try connecting Via IP not name does that work?

Tried that no luck.

Setup while testing was to VPN into my network so it effectively meant I was inside my network from my pfsense firewall. I could ping the ip the exchange server was on by IP but Chrome could not connect to exchange. Nothing could unless I remoted in using RDP into the machine running exchange and used IE on that to connect. This was all while I was at work.

I was all set to do a restore from the last backup when I tested and just as suddenly I can connect with exchange. Chrome browser, iPad, and iPhone all connect fine. Only difference is this was at home inside the network (which the VPN should have been as well).

So if when I go to work tonight and it does not work then it is obviously my Firewall doing something (even though I disabled most of it while testing). If it does work okay then I will be happy but also annoyed as to what the issue was.

bro67 said:

For 2010, but gives you info on how to configure. https://social.technet.microsoft.com...ss-server.aspx
https://docs.microsoft.com/en-us/Exc...xchserver-2019

This one walks you through configuring internal and external IP’s with Exchange 2016. http://www.mustbegeek.com/configure-...exchange-2016/

There is nothing wrong with the exchange setup. It works and has worked for many years as I can read email internally on my LAN network. Just can't get to it from my WAN network.

It appears to be my firewall but don't know why as nothing changed but suddendly it won't let port 443 through even with VPN into the network.

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After checking my firewall several times I could not see anything that would stop it from allowing port 443 to my exchange server. However I grabbed a backup configuration file and restored the firewall to that point just over a week ago and once again mail is flowing correctly.
I believe it was HAProxy even though it was only configured for port 80 for letsencrypt certs to get through to two separate computers.

Will start reinstalling HAProxy and see what happens. Maybe it corrupted something in the firewall rules.