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Forum Discussion

nasgulch's avatar
nasgulch
Aspirant
Feb 01, 2022

Nighthawk M2 IP Passthrough Netmask incorrect

I am using my M2 with IP Passthrough activated to provide the WAN to another router. Receiving Router is set to DHCP for the WAN port.

The M2 shows the proper IP adress coming from my ISP with a subnet mask of 255.255.255.0 

Unfortunately when it arrives to the router it shows mithg the right adress but a subnet mask of 255.255.255.255

IP received by RouterIP as seen on M2

 

I can fix it by setting a static IP with the proper mask in the router. But since my ISP changes the public IP every so often, it is not reliable.

Is there a way to overwrite the IP passthrough Address Netmask in the M2?

M2 is on latest FW 24_10.17.08.00

Any help is appreciated

Erik

 

Any help is appreicated

4 Replies

  • nasgulch's avatar
    nasgulch
    Aspirant
    Feb 01, 2022

    I just realized that the M5 Nighthalwk has a paramter in the settings for IP Passthrough called LTE Subnet Mask

     

    Can we expect an ulgrade of FW for the M2?

    That would be the answer to my issue

    Erik

    • SpiritF's avatar
      SpiritF
      Aspirant
      May 19, 2025

      Hi Eric,

       

      Did you ever manage to resolve this?  I still have this problem with my M2 I have just activated again in Passthrough mode.

       

      Thanks

      Roger

  • schumaku's avatar
    schumaku
    Guru
    May 19, 2025

    Unless you have a special contract with your mobile provider offering multiple IP addresses (this wasn't possible before LTE was introduced), there will -always- only a single IP address will be associated, so 255.255.255.255 with a single address/32 is perfectly correct. 

     

    That means, to connect mor than one device also your mobile hotspot kist either be configured to NAT mode, for passthrough an additional router is required. 

     

    To use the additional public IP addresses you would need a capable router - connected to the Ethernet port - able to deal with multiple IP addresses in your public WAN side.

     

    This isn't a problem of the M2 as the OP supposed.

     

    Regards

    -Kurt.

    ...just yet another community member, not representing Netgear.

     

     

    • SpiritF's avatar
      SpiritF
      Aspirant
      May 19, 2025

      Thanks for the quick reply schumaku.  Much appreciated.

       

      I have the M2 connected to a DD-WRT flashed router, using the M2 as the modem in Passthrough mode, and the DD-WRT router being just the router and local DHCP server etc.

      The problem is that the M2 shows the netmask as 255.255.255.0 but the DD-WRT router detects it as 255.255.255.255.  The public IP address is passed through correctly.

      To get my LAN devices connected to the router to be able to access the internet via the M2 and visa-versa, I have to manually set the WAN parameters on the router and change the netmask to 255.255.255.0 ... in which case everything then works fine.

       

      The problem is when the M2 renews it's public DHCP lease and the public IP changes.  I can then no longer access my network remotely until I reset the router manually.  I can't just reboot it and have it pickup the new settings automatically.