I have run an IPv6 tunnel on FreeBSD for about the last ten years, but over the past month or two, I've experienced slowness over IPv6 and have finally tied it to ESXi. FreeBSD 11 with the latest patches running on ESXi 6.5 build 7388607. I have tried multiple ESXi hosts and had the same result with all of them.
I've tried both the Intel NIC and the VMX NIC with the same issues.
If I run from a desktop running the same version of FreeBSD with the same patches, I get the speed I expect.
From ESXi
root@IPv6Router:/usr/home/carl # wget --no-check-certificate https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz > /dev/null
--2018-04-17 13:23:17-- https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz
Resolving cdn.kernel.org (cdn.kernel.org)... 2a04:4e42:2f::432, 151.101.201.176
Connecting to cdn.kernel.org (cdn.kernel.org)|2a04:4e42:2f::432|:443... connected.
WARNING: cannot verify cdn.kernel.org's certificate, issued by 'CN=GlobalSign Organization Validation CA - SHA256 - G2,O=GlobalSign nv-sa,C=BE':
Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 200 OK
Length: 103016908 (98M) [application/x-xz]
Saving to: 'linux-4.16.2.tar.xz.1'
linux-4.16.2.tar.xz.1 1%[> ] 1.39M 228KB/s eta 6m 58s
From desktop:
$ wget --no-check-certificate https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz > /dev/null
--2018-04-17 09:26:08-- https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz
Resolving cdn.kernel.org (cdn.kernel.org)... 2a04:4e42:8::432, 151.101.33.176
Connecting to cdn.kernel.org (cdn.kernel.org)|2a04:4e42:8::432|:443... connected.
WARNING: cannot verify cdn.kernel.org's certificate, issued by 'CN=GlobalSign Organization Validation CA - SHA256 - G2,O=GlobalSign nv-sa,C=BE':
Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 200 OK
Length: 103016908 (98M) [application/x-xz]
Saving to: 'linux-4.16.2.tar.xz'
linux-4.16.2.tar.xz 35%[=====================> ] 34.56M 9.52MB/s eta 9s
I suspect this is a VM setting somewhere, but don't have the first idea of where to look.
Update:
It's something in ESXi. I downloaded OpenSUSE 42.3 and created a tunnel with the same results
IPv6Router:/home/carl # wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz
--2018-04-19 08:58:55-- https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz
Resolving cdn.kernel.org (cdn.kernel.org)... 2a04:4e42::432, 2a04:4e42:200::432, 2a04:4e42:400::432, ...
Connecting to cdn.kernel.org (cdn.kernel.org)|2a04:4e42::432|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 103011528 (98M) [application/x-xz]
Saving to: 'linux-4.16.3.tar.xz'
1% [==> ] 1,954,169 125KB/s eta 19m 4s