Double NAT Problem


For a proper SQM setup on my network, I wanted to get rid of double NAT interferences. My setup is the following:

4G SIM-card router (TP-Link Archer MR2000 ; running stock firmware) (

Zxyel WSM20 (OpenWrt; V. 23.05.3) --> this acts as dumb AP (

Now there is no option so far on my TP-Link router to enable LAN bridging mode. Both routers are obviously on the same subnet and whenever I try to set a static IP for the OpenWrt router on a different subnet, I get error messages. I am not sure if it would be easier to just flash OpenWrt on my TP-Link router aswell?

we can't work with unknow error messages.

it would, if it had been supported ...
unless you mean MR200 and not MR2000 :wink:

Why do you want to change your current configuration?

What is your problem with double NAT?

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As far as I know it gets you worse results while using SQM cake(autorate).

@frollic sorry yes I mean the MR200, and I just saw that a snapshot version of the V5 exists. Therefore I guess the most easy way would be to flash it in regarding of double NAT settings?

OpenWRT on the dumb AP should work too, I think you can SQM without a WAN port.

It is probably possible to SQM without the WAN, I tried it already before and besides people trying to help me also here on the forum, it was of no success, probably also due to my poor knowledge of OpenWrt and linux. Therefore I believe that it is much easier to just get rid of the double NAT.

If you use OpenWRT on your TP link you can do SQM on that router, maybe that solves your problem?

just keep in mind the SoC in the MR200 is probably weaker than the one in the WSM20.

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Likely domb ap has default codel attached to wan interface, you need to attach that to dsa master handling bridged lan first.

@frollic @egc because of the weak SoC in the MR200 I bought the WSM20, running SQM on the TP-Link one is not really an option.

@brada4 Sorry could you explain this further?

The default sqm is set for wan port, you need to transfer that to present lan port for any effect.

I already setup sqm with cake-autorate on the wan-port and it is working fairly good. I think it can be optimized by getting rid of the double NAT. If I understand you correctly you think I should switch to a LAN-bridge and use the WSM20 as a dumb ap? I don't really know but I thought if would be easier for me just to get rid of the double NAT now.

So the "Dumb AP" in original post means "wireless wan" and you need to properly relocate SQM when you start using router as "Dumb AP"

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Ok, so you mean I should connect both routers by a wireless bridge? I am not sure if I want to use my WSM20 as dumb ap, I rather use it as my main router, hosting wifi networks from this router and just getting the internet connection from my MR200 router.

No, the WSM router just bridges LAN and WIFI and has IP address in casual DHCP network provided by fritzos. Can be client, or static, you hhave to deactivate openwrt's DHCP server.

If you really want to have the WSM20 on its own subnet so connected with the wan to the tp-link it is possible to disable NAT if and only if you can set a static route on the tp-link.

Suppose you set the WSM20 on subnet and its WAN ip is set to (subnet of tp-link is, then on the tp-link you have to add a static route e.g.:
ip route add via

Then you can disable MASQUEREADING (~SNAT) on the WAN zone

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my LTE router (TP Link) has the iP adress
WMS 20 OpenWrt has and (I guess assigend by the TP link router)

Would these settings be correcct like that? (Subnet Mask: I entered the one of the WSM20 OpenWrt router

The network destination is
Subnet mask is
Gateway is


Sorry for my dumb questions, but how can I do this in LuCi?

Also is there a way to check if I actually diasabled double NAT?

Network > Firewall > uncheck Masquerading checkbox next to the wan firewall zone