Fourth Day with Mystery MTU Error Message. Turning power off and on not magic solution as advertised.

What Country/State/Province do you live in? California, United States

Modem brand & model number: Speedstream 5100b

Router brand & model number: n/a

Network Connection Type: Wireless/Wired: Wired

If Wireless, what type of encryption are you using? n/a

Things you have tried: all listed on support page

1. power cycling

2. plugged directly into modem as always

3. Changed MTU to 1490 as recommended

4. Checked all connections

Is UPnP Enabled? Yes/no/Unknown: unknown Enabled where? I'm plugging directly into modem.

Is NAT Type Open? n/a

Any Error Codes you encounter: Insufficient MTU

What type of internet do you have? Cable/DSL/T1/3G? ADSL

Who is your ISP(Internet Service Provider)? ATT

When you run "Test Xbox LIVE connection" what is the exact message shown on screen?

Your network connection has insufficient MTU. MTU must be at least 1364. Change settings or plug directly into modem.

Endlessly turning the power off and on doesn't appear to be magically fixing this. The XBox 360 does not advertise itself as being only for network engineers. I'll keep this in mind for future purchases.

 

Question Info


Last updated July 4, 2018 Views 2 Applies to:

MTU isn't a Xbox setting, it's just a requirement for it to maintain a certain certain packet size, it helps maintain the quality of your gaming connection.

Most commonly with DSL it's going to be an issue with a filter on the line, the gateway they gave you starting to go out or in some cases it's also what pops up when your connection is being throttled for billing issues with the ISP.

Though the biggest problem with testing that is mainly that DSL companies don't hand out modems, they give gateways what are demi-routers. Even if there is only one port on the gateway it still has firmware on it that can have issues like any router and doesn't in that case fully test if it's a line issue or not by plugging directly in.

What did your ISP say when you called them?

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"it's going to be an issue with a filter on the line" "the gateway they gave you starting to go out" -Please tell me how that in any way gets anyone closer to playing XBox Live.

How does one find an "issue" with a filter on the line?

Did the modem just get sleepy?

This connection was working fine when the console quit working two months ago.

This modem has been doing XBox Live for two years. Streaming Netflix and playing games just fine.

It is the same DSL connection.

Same passwords, same everything.

I unplugged the XBox 360 and sent it to be repaired. Twice. Still don't know what, if anything, they fixed.

When it came back I connected it back exactly as it was working before.

Connection test says it sees the internet but then stops with the MTU error at the next test.

My AT&T DSL bill is paid and is working fine for everything else. I am using it now for this and I was playing Rift last night. No slowing or issues at all.

Everything is the same as it was before except the console was shipped in to be repaired.

AT&T says the connection has no issues. Nothing has changed. The tech support rep told me it has nothing to do with my connection.

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Well that tech support rep was wrong. Of course they won't admit fault, most of the time it's because they undertrain their techs. MTU isn't an xbox specific setting. It is part of the internet, just like DNS, just like IP addresses. Some things the xbox can attempt to control like the IP address or the DNS but the MTU can't be device specific, it has to be run by the company supplying the connection or the router managing it.

I'm sorry that you seem to have run into this issue after you had your console repaired, but I can guarantee you that MTU is NOT a setting on the xbox, it merely tests to make sure it can send large enough chunks of data at a time to keep a solid connection to games.

If you're not going to check anything though, I say thank you for being stubborn and for throwing what other network technicians HAVE documented as causes of the issues you're running into out the window. You obviously know what you're doing since you're posting here. I was nice enough to offer information that has proven to be related to network setups I've troubleshot. Obviously you do not need the assistance though, so have fun with that.

If you are still looking for help however you can try using a search engine to do your own research on it - and how to verify if your connection is having MTU or large packet issues. Might even be able to find somewhere a command line or something that you might be able to run on your setup that uses the packet size that the xbox is saying it needs. Then again those are just possibilities. Good luck.

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