MTU Size

savualexandru · 2022-03-15T10:01:58+00:00

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savualexandru

Hello gentlemen, I am having some issues with the internet connection, it is unstable at best, and I want to ask what the MTU and MSS values are used in UPC ?

The UPC Giga Connect Box is set to 1500, my local network also at 1500, so I can’t really test if this is the correct value towards the internet from the modem.

The behavior is consistent with dropped packets but it can also be related to fragmented packets, and before I dive further into troubleshooting this, I need to know whether 1500 for MTU/MSS on WAN side is the correct setting for UPC.

I am using the UPC Giga Connect Box with IPv4, in Router Mode, after it I have another router (OPNSense), both perform NAT.

Also, is it possible to change the IPv4 address class for LAN/NAT on the Giga Connect Box?
It looks like it is blocked to the 192.168.0.0 class and I have not found a method to change it.

Thank you.
Looking forward to your reply.

Kind regards,
Alexandru

Daniele_Sunrise

savualexandru Our modems have the 1500 MTU value. So all your devices should also have this value set.

The IP range can be set from 192.168.0.2, because 192.168.0.1 is reserved for the modem. We have also checked the signal quality of your connection and it could be levelled even better. We have created a technician order in this regard. You will be contacted for an appointment within 24 hours.

Please contact us after the technician visit with feedback.

Greetings
Daniele

savualexandru

Daniele_Sunrise

Hello Daniele, thank you for your reply, indeed the modem and all my subsequent equipment have 1500 MTU set throughout.

I am surprised that your checks revealed some room for more finetunning this connection on your side.
Can you provide more details regarding this please ?
What does “levelled even better” mean ?

Also, thank you very much for being so proactive and involved.

I am looking forward to the technician’s call and visit.

Kind regards,
Alexandru

Daniele_Sunrise

savualexandru he signal of the downstream (download) is not clean and in the graph you can see that several days your signal is in the upper and lower area of the red marked field, which would not be optimal.

Greetings
Daniele

savualexandru

Daniele_Sunrise Thank you Daniele, for the details.

Yes, it looks like there is something going on there, I am thinking noise wise is not as desired, but download wise here, I can reach Gigabit speeds. Hopefully it will be smoother after it gets finetunned.

Also your colleagues called and someone is supposed to come and look into this tomorrow morning. Looking forward to it.

Thank you Daniele, I will post the results of tomorrow’s intervention, afterwards.

Kind regards,

Alexandru

savualexandru

Hello Daniele,

I hope my message finds you well.

Your colleague was here, fiddled with the box downstairs, checked the signal I guess, changed a coax connector and he was done.

After this, I restarted the Connect Box, and I can say that the throughput is the same for both download and upload streams and my OPNSense router shows an improvement on gateway monitoring in ms, by about 2ms RTT.

Can you please take a look at the new values shown as in the Power-Downstream graph above and post them here ?

Great support from UPC, fast and reliable.
The technician that came here today, arrived at the previously agreed timeframe and on time, and he was a real professional about it.

Thank you very much for your help Daniele, and thank you UPC.

Kind regards,
Alexandru

Daniele_Sunrise

savualexandru The signal looks much better. This is evident in the curve, which now goes down into the normal range.

Greetings
Daniele

savualexandru

Daniele_Sunrise Thank you Daniele! 😁