This method requires no software, no fancy router settings/models, and doesn't affect any other devices on your network. It works in sleep mode, too.

1. On your PC, go to OpenDNS.com and start up a free account: https://www.opendns.com/

2. add a network and use the default IP that shows up: https://dashboard.opendns.com/settings/
*This is your modem's IP, not your PC's IP. you can double check at http://www.whatismyip.com/

3. Click your IP address as it's listed to go to your CONTENT EDITING page. Keep the categories set at NONE but add these individual domains near the bottom to block:
nus.c.shop.nintendowifi.net
nus.cdn.c.shop.nintendowifi.net
nus.cdn.wup.shop.nintendo.net
c.shop.nintendowifi.net
nus.wup.shop.nintendo.net
nus.cdn.shop.wii.com (*may prompt a "block entire content delivery category?". Choose No/Domain only.)


4. On your 3DS: System Settings > Internet Settings > Connection Settings > Connection # > Change Settings > DNS > Auto-Obtain NO > Detailed Setup

5. Set Primary DNS to 208.67.222.222 and secondary to 208.67.220.220

6. Enjoy life

In case it's not working:
Are you using another DNS? If you have a custom DNS (such as google DNS) setup on your router, this might not work. You can clear the router's DNS settings and set up Google DNS on your PC to keep using GoogleDNS with your computer, and OpenDNS from your 3DS.

Be sure to disable any proxy or VPNs for Step 2. Don't know if you have one? http://www.whatismyip.com/ will tell you if it detects a proxy, and if it's giving you incorrect location/ISP details, you might be running a VPN/proxy.

You might have a Dynamic IP (a home IP/step 2 IP that changes once in a while). OpenDNS has documentation on how to deal with this.'

OpenDNS only offers one free IP setup per account. If you connect to another router OpenDNS won't be able to block the request. (I will explain why this happens in more detail later)

Disclaimer: I know a thing or two about routers, but it is a hobby, not a profession. I might be wrong about the domains blocked. I appreciate any input to make this right in case I'm wrong. So far I haven't been pinged to update, but I also haven't tried to force the update check either. If anyone knows for certain what domain to block, please let us all know so I can edit this post. If the 3DS pings an IP instead of a domain, this OpenDNS method is worthless, but apparently that's not the case so we should be okay.

Spotpass/Streetpass/Homepass Warning: Spotpass will ping the update. Because spotpass hotspots are preconfigured into every 3DS, it will not use OpenDNS. This method will not protect you from downloading the update over spotpass. Also, this is just speculation. Feel free to confirm/disprove this for the rest of us. Homepass can be configured to use OpenDNS, but it's not something I'm going to get into because there are too many unique ways to homepass.

 

[cvskid]

So am I right to say that this ONLY blocks the eshop?

What about online play within games themselves? No block right?

Online play works just fine for me with multiple games. Just hope super smash bros doesnt get another update patch. Other games are good though.

 

[Arithmatics]

Online play works just fine for me with multiple games. Just hope super smash bros doesnt get another update patch. Other games are good though.

If it gets an update patch can you still play it or do you HAVE to update it to be able to play it?

 

[cvskid]

If it gets an update patch can you still play it or do you HAVE to update it to be able to play it?

You will be able yo play it but offline only, nintendo forces everyone to have the most recent patch of the game to be able to play it online.

 

[TidusWulf]

It blocks a few things. pecifically the Nintendo Update Server (the NUS in those domains) so that it won't find an update while in sleep mode

It also blocks the eShop from downloading the update so even if you got a notification (perhaps due to spot/streetpassing) once you're back on your home wifi, it won't be able to access the eShop and download the update.

I can confirm from firsthand expereince that it does NOT block online play. HOWEVER, any games that have pending eShop updates (smash bros, pokemon, etc.) will block you from playing online. As long as all your games are up to date, they'll play online (until they are out of date). If you have smash bros update 1.0.4, it's okay if you're still on 9.2.0 firmware. But once smash 1.0.5 comes out, you'll have to update. Sadly, eShop won't give you the 1.0.5 for smash until you first download 9.4.0 for the 3DS

 

[TidusWulf]

Someone told me that spotpass doesn't just ping the update, it'll download it in the background as well. If that's the case, please be extra careful if you get a notification for the update. It won't INSTALL without your consent, but if it downloads the whole thing from spotpass while sleeping, it won't need internet to apply the update once you click ACCEPT.

EDIT: Depends on whether or not you've allowed spotpass auto-downloads. just check your network settings.

 

[davhuit]

It blocks a few things. pecifically the Nintendo Update Server (the NUS in those domains) so that it won't find an update while in sleep mode

It also blocks the eShop from downloading the update so even if you got a notification (perhaps due to spot/streetpassing) once you're back on your home wifi, it won't be able to access the eShop and download the update.

I can confirm from firsthand expereince that it does NOT block online play. HOWEVER, any games that have pending eShop updates (smash bros, pokemon, etc.) will block you from playing online. As long as all your games are up to date, they'll play online (until they are out of date). If you have smash bros update 1.0.4, it's okay if you're still on 9.2.0 firmware. But once smash 1.0.5 comes out, you'll have to update. Sadly, eShop won't give you the 1.0.5 for smash until you first download 9.4.0 for the 3DS

Or if you avoid updating to use the gateway, once it's released, just wait until someone release the update as a cia file and here you go.

Someone told me that spotpass doesn't just ping the update, it'll download it in the background as well. If that's the case, please be extra careful if you get a notification for the update. It won't INSTALL without your consent, but if it downloads the whole thing from spotpass while sleeping, it won't need internet to apply the update once you click ACCEPT.

I can confirm it. My other 3DS (9.2) downloaded the update itself and when I launched it to see what it says, it's written you don't need internet to update.

But since I disabled spotpass (already two days), I didn't got any new update prompt so I wonder if disabling it delete the update or not, or at least block the update prompt.

 

[Kino Akuro]

just to be clear if i play on my home with my wifi, and i disable the spotpass feature on my 3ds it won't download the update, rigth? or will it anyway?

 

[davhuit]

It shouldn't, as spotpass is what enable automatic downloads.

 

[cvskid]

It shouldn't, as spotpass is what enable automatic downloads.

Spotpass is what happens when the 3ds is turned on but is closed right?

 

[Arithmatics]

Spotpass is what happens when the 3ds is turned on but is closed right?

and also with wireless capabilities on too.

 

[davhuit]

Spotpass is what happens when the 3ds is turned on but is closed right?

Can't confirm that it only work in sleep mode because I once got several japanese software downloaded on my home screen without being in sleep mode.

And as Streetpass works even when you aren't in sleep mode, dunno if Spotpass is the same.

But basically, as it's written in the settings, spotpass if what let the 3DS download things itself.

http://nintendo3ds.wikia.com/wiki/SpotPass

 

[kheldar]

So a quick question. How do i test this on my console?

edit : I mean It works on some random url I tried but how can i make sure that it blocks the update servers?

also DNS servers I'm using are : 208.67.222.123 and 208.67.220.123

As suggested here

 

[TidusWulf]

So a quick question. How do i test this on my console?

edit : I mean It works on some random url I tried but how can i make sure that it blocks the update servers?

also DNS servers I'm using are : 208.67.222.123 and 208.67.220.123

As suggested here

I use these. https://store.opendns.com/setup/#/ since it seems the most universal for what OpenDNS is designed to do.

Also, you can test by going to the eShop. if it's working, you can access eshop, and it won't prompt an update. it'll just error out. Even if it's NOT working, going to eShop won't force the update (but it will start nagging for the rest of your 3DS's life lol)

 

[TidusWulf]

Can't confirm that it only work in sleep mode because I once got several japanese software downloaded on my home screen without being in sleep mode.

And as Streetpass works even when you aren't in sleep mode, dunno if Spotpass is the same.

But basically, as it's written in the settings, spotpass if what let the 3DS download things itself.

http://nintendo3ds.wikia.com/wiki/SpotPass

spotpass has a setting which you can set wether you want it to auto-download software and updates. You can opt out of auto-downloading the update, but you can't opt out of CHECKING for the update.

 

[kheldar]

I use these. https://store.opendns.com/setup/#/ since it seems the most universal for what OpenDNS is designed to do.

Also, you can test by going to the eShop. if it's working, you can access eshop, and it won't prompt an update. it'll just error out. Even if it's NOT working, going to eShop won't force the update (but it will start nagging for the rest of your 3DS's life lol)

I don't want the nag <.< That's why I've been sturggling with this. Is there a way to safely test it? Also I have a problem I have Dynamic IP, I installed the software but It doesn't update my IP. So everytime I restart my router ( which happens a lot because I have a shitty connection) the software says it's updated but I need to go to Dashboard and manually update it there and wait some time,flush my dns cache in order to get it working. I don't have a firewall except windows firewall and I added Opendns software to exclusions list.

 

[TidusWulf]

I don't want the nag <.< That's why I've been sturggling with this. Is there a way to safely test it? Also I have a problem I have Dynamic IP, I installed the software but It doesn't update my IP. So everytime I restart my router ( which happens a lot because I have a shitty connection) the software says it's updated but I need to go to Dashboard and manually update it there and wait some time,flush my dns cache in order to get it working. I don't have a firewall except windows firewall and I added Opendns software to exclusions list.

There isn't a good way to test without risk of nag. As for Dynamic DNS, it's not a problem I've needed to worry about, and so it's not a problem I know the answer to. sorry, man.

 

[Aliahan]

But since I disabled spotpass (already two days), I didn't got any new update prompt so I wonder if disabling it delete the update or not, or at least block the update prompt.

This worked for me, too. I was getting the update nag every day, then I disabled SpotPass and restarted the system. It's been a few days and I haven't had an update nag since then.
Edit: Nevermind, the nag is back on the 4th day. It happened without ever connecting to the internet during that time, so the update must still be in the system's cache. I wonder if it came back for Davhuit, too?

 

[Liberty]

If you have a custom IP and a router which supports adding DynamicDNS-services, you can use such a tutorial:

https://support.opendns.com/entries/25793520-Dynamic-Update-the-IP-use-of-own-URL-
http://www.pc-leicht.com/2010/05/opendns-mit-fritzbox.html

Basically you register on OpenDNS and e.g. noip.com. Add both logins to dnsomatic.com and then use this template:

Service: User defined
Domainname: The hostname from the other DDNS service, e.g. yourhost.dyndns.org
Update URL: updates.dnsomatic.com/nic/update?myip=<ipaddr> (exactly so for Fritz!Box, not as of above!)
Username: Your OpenDNS/DNS-O-Matic user name or e-mail address
Password: Your OpenDNS/DNS-O-Matic password

in your router. On your SysNAND you use 208.67.222.222 and 208.67.220.220 as your DNS. On your EmuNAND you use the normal DNS, e.g. Google public one or whatever you want to.

This is perfect now, because my SysNAND will never be able to update by accident, but I can use everything on EmuNAND just perfectly.

 

[jeppad]

One question:

Can I use this to download demos from the e shop, by blocking updates?

Im on 8.1E

 

[Liberty]

One thing is strange. I blocked the stuff and my SysNAND gave me an update nag today. How is this even possible?