Gateway server experiencing degraded performance

[Andrew K Adams <akadams%psc.edu@localhost>]

Hi, I’ve noticed a problem with my NetBSD server that I really could
use some help with.  The server is acting as my home router (gateway)
in ‘pass-through’ mode with Comcast Xfinity as the service provider.
The only functions/services enabled on the server are: ip-forwarding,
dhcp-client, and NTP.   And on the internal-facing lan: NAT, DHCP, and
SSH.  The internal network supports 5+ wired hosts & 10+ wireless
devices.  I currently have the 1Gig option with Comcast and when
things are operating as expected, I see from an internal (wired) host
750mbs of throughput according to Comcast’s Xfinity speed test
website.  The problem is that performance doesn’t last.  In anywhere
from 3 weeks to 24 hours, my network performance (again, using the
same wired host measured by Xfinity’s speed test) will drop to ~20mbs.
And the change is clearly observable in all networking applications,
e.g., Netflix.  I’m querying here, though, because the fix I’ve found
is to reboot the server.  Upon reboot, I immediately go back to
750mbs.  Hence, I’d like to figure out how to troubleshoot what on my
server is (eventually) degrading my network performance.

The server is relatively new; I built it using an ASUS Mini ITX with
two onboard GigE ethernet ports.  Here’s some relevant dmesg output:

[     1.000000] NetBSD 9.1 (GENERIC) #0: Sun Oct 18 19:24:30 UTC 2020
[     1.000000]
mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC
[     1.000000] total memory = 3457 MB
[     1.000000] avail memory = 3380 MB

[     1.025286] wm0 at pci0 dev 25 function 0: I217 LM Ethernet
Connection (rev. 0x05)
[     1.025286] wm0: interrupting at msi2 vec 0
[     1.025286] wm0: PCI-Express bus
[     1.025286] wm0: 2048 words FLASH, version 0.13.4
[     1.025286] wm0: 0x6a4480<FLASH,IOH_VALID,PCIE,ASF_FIRM,AMT,WOL,EEE>

[     1.025286] re0 at pci3 dev 0 function 0: RealTek 8168/8111 PCIe
Gigabit Ethernet (rev. 0x0c)
[     1.025286] re0: interrupting at msix4 vec 0
[     1.025286] re0: using 256 tx descriptors


And from ifconfig (note, I’ve removed my IP & MAC address from the output):

iquitos# ifconfig -a
wm0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities=7ff80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx>
        capabilities=7ff80<TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Rx>
        capabilities=7ff80<TCP6CSUM_Tx,UDP6CSUM_Rx,UDP6CSUM_Tx,TSO6>
        enabled=0
        ec_capabilities=17<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,EEE>
        ec_enabled=2<VLAN_HWTAGGING>
        media: Ethernet autoselect (1000baseT
full-duplex,flowcontrol,rxpause,txpause)
        status: active
        inet X.X.X.X/20 broadcast 255.255.255.255 flags 0x0
        Inet6 X%wm0/64 flags 0x0 scopeid 0x1
re0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities=3f80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx>
        capabilities=3f80<UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        ec_capabilities=3<VLAN_MTU,VLAN_HWTAGGING>
        ec_enabled=0
        media: Ethernet autoselect (1000baseT full-duplex)
        status: active
        inet 10.19.34.1/24 broadcast 10.19.34.255 flags 0x0
        inet6 fe80::728b:cdff:febc:831b%re0/64 flags 0x0 scopeid 0x2
lo0: flags=0x8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33176
        inet 127.0.0.1/8 flags 0x0
        inet6 ::1/128 flags 0x20<NODAD>
        inet6 fe80::1%lo0/64 flags 0x0 scopeid 0x3


I’m not sure what other information would be useful, just let me know,
and thank you in advance for help you can give me!


Andrew

--
Andrew K. Adams, MCS, MIS
CISO, NSF Cybersecurity Center of Excellence / trustedci.org
PISO, Security Manager, Pittsburgh Supercomputing Center / psc.edu
Carnegie Mellon University
akadams%psc.edu@localhost / +1 412-268-5142