Can’t sign-in to PSN on PS4, change MTU settings
If you still can’t sign-in to PSN on PS4, or PS3, then you might just need to change your MTU settings and give the console a reboot. The latter is recommended by Sony officially, although the majority of gamers have had success just by heading to setting up an internet connection and changing the MTU option in settings.
The NW-31456-9 error code is one of the most seen right now for those having problems getting PSN to sign-in on their console for today, December 29, or in fact most of the latter part of this month.
Within the last 14 hours, Sony said that PS4 and PS3 owners should “reboot the console” if they are having issues “signing in to PSN today”. This has had mixed results, but on our PSN status page you can see Down Today readers talking about changing the MTU setting to 1450, 1472, or something similar.
It’s normally set at 1500 for most people, but this change seems to fix the PSN sign-in problem for most gamers. This is especially the case with PS4, although one Twitter user replied to Ask PlayStation by saying “starting your console in safe mode didn’t work, I got mine working with MTU set at 1473”.
We’d love to see your current status for either console left at the above page, also if just changing the MTU setting worked and at what setting. It’s interesting to see most people finding a restart not to work as much as changing the network option.