I am relatively new to the company and am troubleshooting slow VPN issues.
We use a Sonicwall NSA 4600 with AD authentication for VPN.
Connection speed in the office is good running through the same firewall.
Users are reporting extremely slow connection speed when connecting to VPN. This is confirmed for multiple users on different connections all getting slow speeds on VPN.
Does anyone have suggestions on where to start troubleshooting?
Much appreciated!
Are the users complaining about slow SMB performance? Are they using the SSLVPN?
If you can afford to move them over to the Global VPN solution, that tends to have better performance for SMB (File and Print Sharing) connections than the SSLVPN.
Newer NICs with RSC caused us many slowness problem. Older NICs didn’t get those kind of problems.
Latest GVC (global vpn client) seems to have fixed it.
Assuming it’s only on wifi, can find the solution here: https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/wifi-issues-with-creators-update/4a20ba4f-33dc-4397-9823-e12dcb2607ba?auth=1
Quick and easy fix in PS:
Get-Netadapterrsc : Finds interfaces that have Receive Segment Coalescing enabled
Disable-netadapterrsc “Interface Name”
Been fighting this issue for years as driver updates break it again
Is the firewall inspecting the packets?
It should not, as they are encrypted.
I’m seeing file transfers max out at about 5MB/s (~40Mb/s) over a home connection of 100/10. My uploads use the whole 10Mb but downloads from work to home top out as stated. I’ve always figured it’s just VPN overhead, plus most of our users aren’t doing a lot of data transfer. FYI, work is a 200/200 fiber line so I don’t expect that’s the bottleneck.
I’ll keep an eye on this post to see what others think, though.
Sonicwalls are fairly plug and play. Maybe upgrade the firmware or rebooting it might be a sollution. VPN will generally always be a little slow, but you may want to check and see if your circuit is actually being maxed out.
afford to move them over to the Global VPN solution
Is this a paid license? Is the Sonicwall-brand “SSL” VPN TCP only?
It’s an issues with SMB over SSLVPN, it’s a known issue with SonicWALL SSLVPN, the newer firmwares improve this, or the SRA appliances.
It is actually due for a firmware upgrade, so gonna try that and reboot later tonight. Thanks!
Was on the phone with SW support recently for an unrelated issue. The tech mentioned your exact issue on one of the more recent firmwares. If I remember correctly he said firmware 6.5.4.6 can exhibit slow sslvpn performance. For our issue, we were running 6.5.4.5 and told to upgrade to 6.5.4.7, bypassing .6 all together.
You want to make sure you go to at least 6.5.4.7-83n. This will help you rule out attackers using your firewall as POC before a global rollout.