Nighthawk issue with PS4. Can't update & IP fragmentation error message

I've gone through the forum posts and tried a few things; Disabled SIP ALG, set MTU to 1488 on PS4, yet I'm still getting very slow speeds on the PS4 speed test and I'm unable to download any game updates.


Can anyone reccomend any other steps I can take? I'm with Plusnet in the UK and apart from the PS4 have absolutly no other issues with the router.


Thanks for any help! 

Model: D7000|Nighthawk AC1900 VDSL/ADSL Modem Router
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Re: Nighthawk issue with PS4. Can't update & IP fragmentation error message

Does your Internet service use PPPoE, PPPoA or L2TP?  If so, you will need to reduce your router's MTU below 1500.  You can use ping tests to empirically determine the optimal value (link).  Read carefully about adding 28.


If this doesn't help, then I've read that double NATing can sometimes be the cause, although I fail to see the connection.  Nevertheless, double NATing is generally not a good idea, so read on.


If the ISP box that your Nighthawk is connected is a combination modem/router, then you could be double NATing.  A telltale sign of double NATing is that the Nighthawk will report an IP address of either 192.168.x.x, 10.x.x.x or 172.16.x.x on its Internet port.  Other clues are that the ISP box has multiple Ethernet LAN ports and/or has its own Wi-Fi.


If you determine that you have a double NAT setup, then you will need to do one of two things.  Pick one option.

  1. Disable the router on the ISP box.  This is usually referred to as putting it into bridge mode.  You will probably need to search online for instructions or call your ISP.  It may not be possible to put it in bridge mode.
  2. Convert the Nighthawk into an AP.  You can enable AP mode under Advanced Setup.

In either case, you will likely have to reboot (actually renewing DHCP leases is enough) your PS4 and any other devices in your network (i.e. computers and smartphones) in order to force them to acquire new IP addresses.


Hopefully, this will resolve your problem.

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