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VPN passtrough speed issue

After my last solved VPN problem I have another one. This is how the network looks like:

UTM1: version 9.580-7, 400/40 internet
UTM2: version 9.510-5, 1000/300 internet

The problem is that if the client with the share connects to UTM2 using L2TP over IPSEC /with Windows 10s built in VPN client/ the file transfer speed to UTM2s network is very slow, only about 3Mbit/sec from the 40 available. If I connect the client directly to the internet /UTM1s WAN cable goes to the client/ the speed is about 35Mbit/sec, so the problem must be on this side. I tried to disable everything /ips, flood protections, portscan, webfilter, qos/ but no change. Can't find anything related in the logs. What could be the problem? Thanks in advance.

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0 BAlfson over 5 years ago

Hoi C F,

What do you learn from doing #1 in Rulz?

Cheers - Bob

Sophos UTM Community Moderator
Sophos Certified Architect - UTM
Sophos Certified Engineer - XG
Gold Solution Partner since 2005

MediaSoft, Inc. USA
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0 C F over 5 years ago in reply to BAlfson

Nothing, because there is nothing related in the logs. I forgott to mention, the speed problem is only there if I upload data from the client, the other way arround the speed is perfect.
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0 BAlfson over 5 years ago in reply to C F

So you confirm that you did look at the logs to confirm that they contained no related lines? Have you tried ifconfig on the interfaces involved in the upload from the client?

Cheers - Bob

Sophos UTM Community Moderator
Sophos Certified Architect - UTM
Sophos Certified Engineer - XG
Gold Solution Partner since 2005

MediaSoft, Inc. USA
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0 C F over 5 years ago in reply to BAlfson

I checked the firewall log, ips is empty ifconfig on the internal nic shows 0 errors or drops on the wan nic there are a few drops and overruns but the number doesn't change if I reconnect and start an upload.

But I have found something. The MTU is 576 on the wan nic and it's not correct /the provider is Ziggo with a docsis 3 network/. Did a test with direct internet connection to the client and the max mtu is 1472 this way, and indeed it's 576 through the UTM. I tried to change the value but after I click save when the nic comes up it's 576 again. This is the only problem I have found but on the other hand every other service works perfectly, speedtest shows maximum results.
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0 C F over 5 years ago in reply to BAlfson

Yes, that was the problem, your comment from here https://community.sophos.com/products/unified-threat-management/f/hardware-installation-up2date-licensing/79288/disable-bad-bugfix-in-9-405-5-fix-nutm-2840-aws-utm-ignores-mtu-sent-by-dhcp-server/372944#372944 helped to resolve it. Thanks!
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