Moving from 150Mb/s Fibre to 900Mb/s Fibre


I am still fairly new to OpenWRT (but very happy so far). So, please be gentle if I am saying/asking things that are dumb.

I have four Zyxel WSM20s. One is the router on a 150Gb/s fibre service, two more are APs in a mesh (cat 5E backhaul will be installed once I get "a round tuit") and the final one is a spare - just in case.......

These were configured with OpenWRT in December 2023 and the setup has been pretty solid.

I am planning on upgrading to 900Mb/s Fibre in the Summer. We have a new ISP in town - so the upgrade should save me around £15 per month, at least in the short term. I am likely to lose out on the quality of technical support from the ISP, though.

Because I like to be prepared, I have read So you have 500Mbps-1Gbps fiber and need a router READ THIS FIRST - #2 by dl12345

As far as I can get my head around it, the Zyxel WSM20 router will not be "man enough" for the increased speed. Have I got that right? I am seeing a CPU speed of 800MHz in the spec for the WSM20 but the post says 1200MHz is necessary for 900Mb/s and more CPU speed that that is desirable.

What am I likely to experience if I put my WSM20 onto the 900Mb/s service? My guess is faster speeds than the 150Mb/s but not 900Mb/s. Can I expect proportional to the CPU speeds (800/1200 x 900 = 600Mb/s)?

Thanks in advance for any advice/input.

I think it is saying you need that much speed just for packets and scheduling with SQM.

But the bottom line is it is going to cost you and we still don't have off the shelf solutions that will satisfy anyone that comes here.

"At 1 GHz processing rate, each packet gets 12000 clock cycles of calculation if the CPU is maxed out doing nothing but processing packets."

Nope, I was wrong; they are saying just processing packets raw, no SQM.

Test ?

If it works, you save some $$$, if not, start looking into additional hw.

Seemingly, I will get a Linksys SPNMX42 when I change ISP. Currently only on snapshots for OpenWRT. Plus they probably won't want me changing the firmware - initially, at least.

I was wondering if a gl-mt6000 might give me full speed?

I think the plan looks like:

  1. Accept the Linksys SPNMX42 in order to commission the service
  2. Put the Zyxel WSM20 in place of the SPNMX42 and see what happens
  3. Look at what is available OpenWRT-wise at that time, if the Zyxel is not satisfactory

Where did you see it's supported?

It would, but since you already got the wireless covered, it's also seriously overkill.

Does it mean you actually have to hook it up ?

Who's the provider, ogi, swish, trooli, Cityfibre, community fibre, Gigaclear,

Are you going to be on symmetric 900/900?

Where did you see it's supported? lists Linksys MX4200 V1 & V2 as snapshot under current supported release

Does it mean you actually have to hook it up ?

I expect to do that for 15 minutes once the service goes live - to prove that is is all commissioned OK. Then I expect to transfer the PPoE settings to the Zyxel and "retire" the MX4200

Who's the provider, ogi, swish, trooli, Cityfibre, community fibre, Gigaclear,

Toob over CityFibre

Are you going to be on symmetric 900/900?

Yes, if their home page (and the experience of my friend who has just gone to Toob from Virgin are to be believed).

Toob use DHCP over WAN, no PPPoE details required.

So that leaves you with deciding what you want to use for the gateway device as a WSM20 would be pushing it if you're having a mesh setup.

GL-MT3000 would give full speed, as would a few others.

I fail to see the connection to the SPNMX42 ... ?

if you want something extendable, have a look at

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The WSM20 has flow offloading support so 900 should be easy.

See here at 12:32 for setup and speed test achieving 900 on WSM20.


MX4200 "customised" for Gigaclear customers?

MX4200 "customised" for Toob customers?

Great suggestion. Thank you.

Doesn't mean the mx4200 firmware will run on it, without additional customization.


The WSM20 has flow offloading support so 900 should be easy.

Thank you. That is incredibly helpful and something that I would not have found out for myself in many years of looking

Which is fine.

Because of what gameinn has posted, I do not plan to try any time soon. :slight_smile:

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