✅ Lower Ping & FASTER Speed By Changing MTU Packet Size? T-Mobile Home Internet - How to Optimize

You can quickly find out your optimal MTU packet size by following along and then setting your router or computer to that size. If its not set properly you can run into packet fragmentation which leads to higher ping and slower speeds (or complete transmission failure). Here I go step by step on how to do that and how that turns out for me on T-Mobile 5G Home Internet. This applies to all ISP's; cellular, cable, satellite, fiber, starlink, etc.

Windows cmd commands for:
Check your computers MTU settings: netsh interface ipv4 show subinterfaces

Be sure to see my other Verizon and T-Mobile Home Internet Videos:

My Asus AiMesh:

#mtupacketsize #networking #tmobilehomeinternet #tmobile #cmd #optimization #howto

[madmaddox]

Just did this change after switching to T-moblie home internet after having terrible ping in gaming. Went from 80-95 ping with a lot of major spikes all the way up to 350+ to doing this mtu change to 1428 (1500 before) and ping is down to consistent 50-58 ping in game. Thank you for the help.

[surfing]

Hey, I am not sure how many of your viewers are having the issue of Connect/NO Internet from Arcadyan Gateway. I discovered a workaround on this issue until T-mobile can fix it. It appears If you run a continuous stream, such as a live feed from a nest cam to a device on the network, such as as android phone the internet will stay up. At the moment my issue is as soon as all connections become "Close_Wait" state, the gateway will drop it connection to the internet. The gateway in this state is able to received text message. This requires a reboot of the gateway. I have tested this for the last 5 days and it work without going down. I did verify the issue by turning off the cams and within 10mins the gateway went back to Connect/NO internet. This issue became very apparent when T-mobile changed our service from band 2/N71 to Band 66/N41. The band change did bring an increase in speed to 600mb/50 without the need of any modifications to the gateway.

[e.jordangottlieb]

With most cable based, Public/Private WiFi, and fiber service providers the MTU value does not need to be changed from 1500. Other types of providers that use PPPoE typically result in an 8 byte overhead leaving you with a 1492 MTU. T-Mobile does indeed have a 1420 byte MTU as relayed by others on this thread. There are indications as reported on the Internet that T-Mobile uses 464XLAT but that does not explain such a low MTU on its own as it does not incur an 80 byte overhead (would be interested to know what that is if others know). The are other service provider scenarios that can impact the MTU such as the use of DS-Lite, LW4Over6, MAP-E, and MAP-T. Your VPN provider (such as Nord or Express) will also impact your MTU size

The ping tool technique utilized in this video is correct and will allow you to set the right MTU on your attached devices. Only problem with this approach is that it typically does nothing to fix the other side of the connection (the server) in most cases for traffic that is not TCP. Most servers assume a 1500 byte MTU and will not adjust if PMTUD is not supported. Therefore non-TCP traffic that is larger than the supported MTU will likely get fragmented by T-Mobile. The MSS term is mis-used in this video as it is a specific header attribute of TCP.

I mention TCP as not being impacted as it is likely that T-Mobile utilizes a technique called MSS clamping on their router to ensure the clients and servers set a segment size that will fit in the 1420 MTU. TCP is more consistent with its use of PMTUD which will ensure proper segment sizing in many cases (even without MSS clamping). So in all these cases it is highly unlikely that you will experience fragmentation when using TCP (which as things stand is the majority of most peoples non-VPN traffic). QUIC which is an emerging protocol that uses UDP (heavily used by google including in youtube) should fit without fragmentation in an MTU as low as 1420

All this being said unless you have a specific excessive fragmentation issue with VPN (or non-function in the case of DF-Bit 1 based VPN) you should avoid messing around with the MTU unless you truely understand your end-to-end environment and all the networking concepts I relay in this comment. There are no performance or functional gains to be had for the vast majority of Internet applications.

[thetravismayo]

Thank you for this I went from 16mb/s to 32mb/s by changing the MTU from 1500 to 1452 and I have just bought the MIMO 4x4 Antenna upgrade as I live in a wooded area in West Knoxville, TN and I only get 2 bars of 5G

[adamponder]

Once you have established the maximum buffer value that you can use, add 28 to that value (to account for the size of the packet header). That will be your maximum MTU value. In my case, the maximum buffer size was 1472. When I add 28, I get the previously mentioned value of 1500. Incidentally, 1500 will usually be the maximum MTU value, but depending on your network, it could be higher or lower.

[scenicnomad]

I've got T-Mobile home internet also and run into similar issues as you. When I contact them they said that some of the routers are having a problem when updating to the latest firmware. Also, it may be to do with how your antenna is aimed. I ended up going with 4x4 MIMO antenna and was able to get a very stable connection once I had everything aimed just right. Good luck with everything and thanks for the informative video!

[clggauthier]

I ditched my recently purchased 😢 eero mesh router to another because the eero wouldn’t allow me to change my packets size. Constantly had “no WiFi available“ issues. Peter Carcione identified my problem and suggested this solution. Since I’ve changed router and set my packet size to t-mobile’s 1420, my WiFi has been consistent and I haven’t had to reset my system for over 2 months. My ping is only slightly better but my zoom video and everything else is solid and stable now. I’m somewhat remote and have mountains blocking signals so as with everything “mileage may vary” with everyone’s specific situation.

[keithr-]

Setting the MTU on your PC will net much better results than setting it on your router. When you set your router to 1420 and your PC is still at 1500, your PC is going to send 1500 byte packets (frames, actually, but not important for this discussion) and your router now has to fragment those packets, which incurs CPU cost and naturally some latency because the router has to stop and do work on that packet before forwarding it. You're just shifting the duty of fragmenting those packets from the gateway to your router, and while your router might be slightly better equipped to handle that task, it's still far from optimal.

When you set the MTU on your PC, the TCP/IP stack (drivers) are only going to build packets of size 1420 or smaller. Neither your router nor the gateway now have to fragment the packets.

Ideally, set it in both places. Set it on your router because not all devices on your network will let you set an MTU, and for those devices the router will do the work to fragment packets when needed, and then for any device where you can set the MTU, setting it on the devices themselves lets the operating system know to only build packets to that size before sending them. As long as the router and other devices are all set to the same value, the router will never have to fragment traffic from those devices and will just pass it on through.

[Justin-hzbh]

In my experience, if you cut a package in half and expect USPS to put it back together, they just wont ship it. You must have an exceptional USPS staff where you live! 🤣🤣
But, thanks for these videos and continuing to look for ways to improve signal and speeds on these units! Much appreciated!

[James_Knott]

Actually, Path MTU Discovery (PMTUD) is used today. It's used for everything with Linux and TCP with Windows. It's also mandatory for everything with IPv6. With PMTUD, fragmentation is not used. PMTUD sets the Don't fragment flag on IPv4. There is no such flag on IPv6, as there's no need for it, because routers are not allowed to fragment.
VoIP packets are generally smaller than even the smallest allowable MTU (576 on IPv4 and 1280 on IPv6).
1500 is the standard, unless you're on ADSL, where it will be 1492, to allow for the additional header. When I first used the Internet, back in the mid 90s, it was 576 over a dial up SLIP connection.
As you mentioned, the speedtest variation is greater than that difference you claim to see. I have seen some really large differences between multiple passes.
I'd suspect your VPN issues are caused by something else. I use OpenVPN, which just adds a UDP header in front of the encrypted packet. NO issues at all.

BTW, if your parcel is to big for USPS, you don't have to worry about cutting it in half. The posties will happily destroy it for you. ;-)

[rifarira]

Can we find out an optimal mtu for a certain activity/program? My internet is fine if used for anything beside online gaming, the moment i do gaming the packet loss is unreal.

[tonynasaofficial]

I honestly don't know why I'm here but I enjoyed this video, now I'm wondering is it possible to make it switch to low packets to high so like when your on a online virtual server it makes it so on there end they interacted with you while on your end they didn't!

[jasondessenberg]

Thanks for the clarification. I had play with my MTU when I was on T-Mobile but did not know about adding the 28. I am on VZW now because my T-mobile kept dropping the connection. I am not seeing a huge increase in speed maybe 10 Mbps down. The ping is a little better too. I had set my router back to 1500 because I could not really find much info on VZW. But video helped.

[mploof]

I just picked my KVD21 up yesterday and setup today. Not a fan of the GUI and lack of settings. I plugged straight into my TP-LINK ARCHER AX11000 Router and working just fine. On my cable internet I was pulling 170/9, with TMO I'm getting 75/18, going through my AX11000 router with OpenVPN enabled on router with SurfShark client. I live alone so speed is just fine at 75/18, my issue was cable internet constantly goes down. We'll see how this works.

[arizonaphotolife]

Sprint used to have reg files (not sure if that was same thing as MTU or not) that could be changed back and forth with way back in the day of Sprint Wireless home internet. Those funny square microwave antenna's you might see on the West coast. Those were the days lol.

[whatsupd]

T-Mobile Arcadian GW and I'm seeing 1480 (1452+28) as the optimum size and it's hard to say if it made a difference ad any speed test change is within the noise in speedtest data

[the-papaw]

Testing MTU size doesn't apply as it should when using any OTA carriers (3G/4G/5G/Satellite) as the signal fluctuates so much. It it more for folks using hard wired internet connections (DSL/Cable/Fiber)

[edsoto]

I wonder if you can recommend a router to use with my tmobile Nokia gateway. I try the DYNALINK which has been spoken about well and the asus RT-AX55 and they generate less speed then the Nokia gateway. TheDynalink being the worst as I only get 1/3 the speed and the asus about 80%. I have busted my head with these two. I change MTU on the Nokia. I cannot change it on the asus because there is no avenue to do so. If you have time, I would appreciate your input. Love your breaking down everything on the T-Mobile stuff.

[mikepruett]

i have at and t and didnt find the mtu on the modem yet any ideas i cant stream to 2 platforms without total choppiness

[beausmith]

Do you recommend a separate router for advanced settings like this? Is the google nest mesh router fine for this?