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So I have a Netgear DGND3800b router (n600) connected with 1.5m cat5e rj45 from a 1 gbit fiber transciever to the fiber/cable port on the router, for some reason I am unable get a speed faster than 280/300.

  1. Over LAN (ethernet) I am able to get 1 Gbit between computers.
  2. Connecting the computer directly with the same cable (5e) to the fiber transciever gives me 1 Gbit.
  3. Wifi gives ~250 (fair enough).

I tried resetting my router, remove firewall and security, single connected device but nothing helps.

The manufacturer states that the fiber/cable port should support 1Gbit.

Any ideas?

Diagram

u1686_grawity
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TTomer
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  • To route 1 Gbit/s, not just any router will do. This requires lots of CPU power or hardware offloading. – Daniel B Mar 12 '23 at 17:03
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    A bit difficult to understand which connections are having this problem. Between two local computers, or from Internet to a computer? Over Wi-Fi or over Ethernet, or both? Please try to add some kind of connection diagram. – u1686_grawity Mar 12 '23 at 17:03
  • @user1686 question edited. – TTomer Mar 12 '23 at 17:11
  • What is this fiber transceiver and where is it placed? It might be simpler to include a schema in your post. – harrymc Mar 12 '23 at 17:13
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    Diagram added.. – TTomer Mar 12 '23 at 17:28
  • In case 1 and 2, were you testing Internet download speed? – u1686_grawity Mar 12 '23 at 17:44
  • In case 1 speedtest shows 300mbps. In case 2 is to check router capabilities by sending files between 2 computers, which shows that the router is capable to handle 1gbps on lan – TTomer Mar 12 '23 at 18:21
  • I hade a mistake in my comment, here ia the correct answer:In case 1 speedtest shows 300mbps theough the router. In case 2 is to check the speed directly, without router and the dl speed is 1gbps – TTomer Mar 12 '23 at 18:32
  • Do you have any QOS settings enabled in the router? This sounds a lot like the CPU not being fast enough to run those types of advanced features with a 1 Gbit pipe. – Coxy Mar 13 '23 at 08:16
  • _"Over LAN (ethernet) I am able to get 1 Gbit between computers."_ - Is this through the LAN ports on the Netgear router? – marcelm Mar 13 '23 at 12:18

1 Answers1

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In case 3, you are not testing the router at all – the PCs are connected only through a Gigabit Ethernet switch built into the router. The switch is capable of independently forwarding packets (or rather whole Ethernet frames) between ports at line rate, and the router's main CPU doesn't even see them. This is standard for hosts that are part of the same subnet.

In case 1, the PC is now connected through the Netgear router's 400 MHz MIPS CPU and the speed is limited by the CPU's capabilities (such types of routers rarely have hardware offload for routing, from what I know). For example, even if you disable the firewall, you're not disabling it completely – the packets still need to be processed for NAT to work (so the firewall's connection tracking system remains active). I do think 300 Mbps is a bit too low but I would not expect it to ever go above (let's say) 600 Mbps or so.

(Also, according to OpenWRT's diagrams, the CPU only has a single Gigabit Ethernet interface which is shared by WAN and LAN ports. In theory this should still be capable of 1 Gbps upload or download – though not both at once – but I still have a suspicion that it doesn't help the situation at all.)

The manufacturer states that the fiber/cable port should support 1Gbit.

Which it does – if you're getting speeds above 100 Mbps, then that means the Ethernet port is certainly running in 1 Gbps (1000BASE-T) mode. (Unlike Wi-Fi, Ethernet has no other modes in-between; if the manufacturer wants to go above 100 Mbps, the closest higher mode is 1 Gbps.)

However, the manufacturer does not state that the router will be able to make full use of that 1 Gbps support. The actual throughput is limited by other components (most likely the CPU).

u1686_grawity
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    In other words you're saying that the manufacturer (Netgear) is misleading and I need to buy a new router? – TTomer Mar 12 '23 at 18:35
  • If I'll install openwrt's project firmware will it give a performance boost? – TTomer Mar 12 '23 at 18:37
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    @TTomer Not really misleading. The problem is people reading too much into it or too little between the lines. – ChanganAuto Mar 12 '23 at 18:44
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    @TTomer Think of it like the many USB 2.0 Gigabit Ethernet adapters. They’re truly Gigabit, but also limited by USB 2.0. // Your router (model) is ten years old. It’s time to get a new one. I have an old WNDR3700 of similar age but superior performance and it can barely do 450 Mbit/s. A newer device will also get you much faster Wi-Fi. – Daniel B Mar 12 '23 at 20:25
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    @TTomer This is a hardware limitation. You may get better performance. You may get worse. Whatever you're getting, it **ISN'T** going to be near 1Gbps. – Nelson Mar 13 '23 at 01:58
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    @TTomer: Having the spec sheet list the port as "Gigabit Ethernet" is completely normal – it's not so much a declaration of speed as it is a declaration of supported modes of operation. It's the rest of the packaging that may or may not be misleading. For example, your Netgear is certainly better than the many routers that advertise "300 Mbps" speed and then only include 100 Mbps Ethernet ports... (again, there is no such thing as "300 Mbps Ethernet" that they could use, it's either 100M or 1G.) – u1686_grawity Mar 13 '23 at 05:52
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    There is such thing as 300 Mbps Wi-Fi. A router like that could in principle transmit between Wi-Fi clients at 300 Mbps and the upstream connection would be limited by the 100 Mbps port. Or more realistically, reach the 100 Mbps between client and Internet even when it doesn't reach the theoretical maximum for wireless part of the route. – ojs Mar 13 '23 at 12:11
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    @TTomer OpenWRT wouldn't help at all. Actually doing NAT/routing at gigabit speeds is not particularly easy, your internet connection is incredibly fast for a home. Some routers advertise an actual NAT/routing speed, which is what you would need. Alternatively a basic PC with two NICs can also easily meet this goal, particularly with more complex routing/NAT rules. – le3th4x0rbot Mar 13 '23 at 22:18