NETGEAR GS108Tv3: Bad internet connection on other VLAN than WAN VLAN

Helly Guys!
I have a bad connection to the Internet on my Switch on a different VLAN as the WAN. WAN has VLAN1(Port1) and my LAN VLAN10.
I configured the device with the informations from the devicesite) .

If i connect a device on a Port with VLAN1 untagged then i have full 100Mbit, if i connect it to the same Port with VLAN10 untagged i have 20MBit. Same with all the other VLANs.

I have already switched the Firewallzones to exclude firewallissue.

If i run i can see the CPU on 100% from the device itself:
(again if i switched the vlan10 to vlan1 on my testport i have 100mbit)
I dont have perfomanceissues beetween the VLANs on the same device.. -H
2022-11-10 22:26:18 Starting speedtest for 60 seconds per transfer session.
Measure speed to (IPv4) while pinging
Download and upload sessions are sequential, each with 5 simultaneous streams.
 Download:  43.01 Mbps
  Latency: [in msec, 61 pings, 0.00% packet loss]
      Min:  14.528
    10pct:  47.927
   Median:  76.808
      Avg:  78.945
    90pct:  95.828
      Max: 496.694
 CPU Load: [in % busy (avg +/- std dev), 56 samples]
     cpu0: 100.0 +/-  0.0
 Overhead: [in % used of total CPU available]
  netperf:  40.2
   Upload:  31.19 Mbps
  Latency: [in msec, 44 pings, 0.00% packet loss]
      Min:  13.893
    10pct:  14.013
   Median: 201.000
      Avg: 203.070
    90pct: 324.665
      Max: 433.900
 CPU Load: [in % busy (avg +/- std dev), 59 samples]
     cpu0:  94.5 +/- 20.2
 Overhead: [in % used of total CPU available]
  netperf:  43.1

Additional Info:
Upgraded the device to 22.03.1 from 22.03: Still only 20Mbit
Upgraded the device to 22.03.2 from 22.03.1: No more Internet connection.

I hope somebody can help me. Didnt see bugs like this in combination with this device..
Thank you in advice

I would advise:

  • Try enabling offloading in the firewall
  • Get a device with a CPU that can handle the traffic
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Eeeeh, are you using the 108 as a router?
That would be a bad idea.


Thanks for fast reply!

Okay im new to networking and networkdevices in general..
I just searched for a device with 8 ports, where i can install openwrt. (looked on amazon and the site from openwrt..)
The Netgear 108Tv3 is behind the modem from the isp.
On Port 1 is the connection to the ispmodem. (VLAN1 defaultconfig) Other ports are for nas, vm-host, accesspoints and 2 pcs with vlans..

Is the realtek-cpu to slow for this job? :frowning:
On the overview site i cant see much traffic. It uses 1% of max connections and the load average is between 0,06 and 0,09

The device is advertised for "VLAN, QoS .." but cant handle my 4 VLANs and some iot-devices?
On the device itself i can move files between the vlans without any performance problem

For routing, no, it's not the intended use case.


Ah okay.
OSI Layer2 is easy to handle for this switch
OSI Layer3 is hard to handle for this switch?

What can i do to fix the problem on budget way or do i have to give it back /sell it and buy a "Router" with 8 ports??

Uses only switch chip.

Uses CPU chip (i.e. firewall/connection tracking/routing).

There aren't many (none?) openwrt capable routers with 8 ports, unless you go for x86.

Your only solution would be to separate the routing, from the switching.

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There is the Asus RT-AC88U with 9 GBit ports, but it's Broadcom-based (the WiFi is working). I had it for one day before selling it again because I was unable to get fast roaming working. VLANs are only supported on 4 or 5 ports, but I think this has been fixed for snapshot builds.

I would keep the switch and buy a simple router - I use an Ubiquiti ER-X with my VLAN switches.

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Thank u very much guys!

The Ubiquiti ER-X is a cheap product with enough RAM and Memory i think?(256MB ram and nand)
If i would buy this, (for my understand) i have to move my interface and firewall config only?


config interface 'IoT'
        option proto 'static'
        option device 'switch.20'
        option ipaddr ''
        option netmask ''

Will be moved to the router (ubiquiti)

and the following:

config bridge-vlan
        option device 'switch'
        option vlan '20'
        list ports 'lan2:t'
        list ports 'lan4:t'

will stay on the switch.

Is this correct? My router is routing between the networks (vlans) and the switch is just for port<>vlan.


Easier method:

1 LAN/VLAN == Switch

If the packet has to cross networks (VLANs), then you're routing. Routing uses CPUs.

I dont understand this... So i cant use multiple VLANs on the switch cause this will use CPU?
For example i want to use 3 different VLANs tagged on 2 Ports on the switch. Other ports untagged. This is not possible with this switch?

The point of VLANs are to isolate networks. So hence, like any other LAN, you must route between them, hence use of CPUs (i.e. routing/firewalling is taking place).

Again, quite simply:

What is your main router? Does it support VLANs (if it is running OpenWrt, it does; vendor firmware may or may not have that functionality exposed).

All of your VLANs should be configured on your main router for the purposes of routing. You'll create a trunk port that goes from the main router to the switch. From there, the switch should be configured such that each VLAN is assigned to the ports as needed (this is the way managed switches are supposed to be used). The switch will ensure that the data flows through appropriately, but the routing itself (i.e. between any two networks and between a network and the internet) should happen on the router, not the switch.

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There aren't many (none?) openwrt capable routers with 8 ports

There are a few non-Intel based devices supported. Mostly Ubiquiti devices:

  • Ubiquiti EdgeRouter (ER-8) Cavium Octeon CN6120 - Dual-core MIPS64
  • Ubiquiti EdgeRouter Pro (ERPro-8) Cavium Octeon CN6120 (adds an SFP port) - Dual-core MIPS64
  • Ubiquiti EdgeSwitch 8XP (ES-8XP) Atheros AR7242 (so likely not a great performer) - MIPS 24kc
  • WatchGuard Firebox M300 NXP QorIQ T2081 - Quad-core PPC64
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