SMB Weirdness

Mercutio

Fatwah on Western Digital
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Jan 17, 2002
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I am omnipresent
I did an in-place upgrade from Server 2008r2 to Server 2012r2 for my main workstation a few days ago and I've been fighting with something weird ever since.

My file server runs Server 2012 (not r2) and is normally connected 24x7 to an OpenVPN end-point. It's been running that way for a couple years now. The other machines in my apartment don't have a problem communicating with that machine and neither did my main workstation until I switched to 2012r2.

If the VPN on the File Server is disconnected, or at any time prior to my recent upgrade, I could push around ~180MB/s between those two machines over SMB thanks to teamed GbE NICs and a good switch.
If the File Server is connected to the VPN, the SMB transfer throughput between the two systems drops to ~100kB/s, not even enough to reliably listen to a FLAC over a gigabit LAN connection.

Again, other systems in my apartment, including Windows 8.1 systems, work fine. Ping (< 1ms ping) and tracert (1 hop) are completely normal regardless of whether the File Server is on the VPN or not.
Name resolution is likewise as it should be and works fine with or without IPv4 or IPv6.

I turned off SMB signing and the option and some driver- and network adapter-specific settings that are occasionally implicated in slow SMB transfers and Windows Firewall is allowing that connection on both sides, VPN or not.
NIC binding order (both machines have multiple NICs) has been examined and found not to matter.

Now, back in the days of XP, being connected to a VPN would route all internet traffic through the VPN. But anything Vista or newer only routes traffic destined for the VPN through the VPN and leaves LAN traffic unmolested. In any case, nothing changed on the file server anyway.

I can't think of anything new in Server 2012r2 that would be doing this and it's clearly just a problem in this one computer but I'll be damned if I can think of what else it might be.
This is the kind of thing that makes me hate in-place upgrades, but after testing out a bunch of 2008 to 2012r2 on VMs, I never actually had a problem until I did it on my own machine.

Anyone have any ideas?
 

Mercutio

Fatwah on Western Digital
Joined
Jan 17, 2002
Messages
22,228
Location
I am omnipresent
... and rolling back to Server 2008 made the problem go away. Note to self: Never, ever upgrade Windows. Clean installs only.
 
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