Different download speeds - Ipfire behind modem, Ipfire via modem mode

Hello friends.
I’m sorry that my English is not perfect.
If this post is in the wrong category, please move it.

Ipfire upgraded or fresh installation of 154 or 154 Repository testing - same symptoms.
My ISP connection - download up to 500Mb/s , upload up to 30Mb/s
via modem Connect Box CH7465LG-LC
The modem has two operating modes - router mode and modem mode (bridge).
My IPFire Fireinfo https://fireinfo.ipfire.org/profile/47c56029f9c77915d42580570346e9f509ba42de

When ipfire is connected “directly” via modem mode,
download is about 220Mb/s , upload is about 30Mb/s.
(INTERNET–modem–dynamic public IP on RED–ipfire–GREEN with private IP 10.10.10.0/24)

When ipfire is connected behind modem in router mode,
download is about 500Mb/s, not less than 400Mb/s , upload is about 30Mb/s
(INTERNET—–dynamic public IP on WAN–modem in router mode–LAN with private IP 192.168.100.1/24–dynamic private IP on RED–ipfire–GREEN with private IP 10.10.10.0/24)

minitests
-swapping MAC addresses (RED GREEN) does not change anything
-laptop, connected “directly” via modem mode - download is about 500Mb/s
-laptop, with MAC from RED ipfire (LocallyAdministredAddress)
connected “directly” via modem mode - download is about 500Mb/s

I’m afraid I don’t understand that :confused:
(is it a bug or a feature… :wink:)

Regards

Sounds like the MTU setting is not configured.
Maybe try setting the modem/router back into modem only mode, then do a search for finding the MTU size on the internet.
There are many guides out there on how to find the MTU size.

MTU size can be set from the IPfire console running setup,
under setup go to Networking then Address Settings, then select the RED interface, You will see an option “Force DHCP MTU”
Set the MTU size you found there.
I think that is the likely issue.

Hope this helps, please let me know.

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Hey, it may be easier if you search in your modem, you may find the MTU size in there.

Hi @tphz

You should have a look at this link before you invest more time at resolving your problem.

2 Minutes of reading

Yes that was worth reading, if there are still no firmware updates to resolve the exploits you should consider a replacement modem.

But this doesn’t explain the behaviour described.
I suppose a MTU problem too.
Looking at the packet flow should show a series of long ( the smaller MTU ) and short ( the diffenrence to the bigger MTU ) packets.

The modem belongs to my ISP :neutral_face:
edit: but “my” firmware is newer than 4.50.18.13-NOS

In modem MTU=1500

I try IPfire unstable version - Download unchanged :neutral_face:
I reinstalled IPfire 154 and I entered this value 1500 in the setup IPfire. - Download unchanged :neutral_face:
I tried entering different values 1460, 1472, 1000 - Download unchanged :neutral_face:

I left the value as it was in the modem - 1500

Then I got the idea…
I set, IP address, gateway, mask, received from DHCP my ISP
to static, in setup IPfire - Download changed to about 500Mb/s :flushed:

That is strange on the speed difference between static and DHCP, don’t
forget to change back to DHCP quickly before it causes problems.

Fireinfo appears to show you have two Intel I350’s and a Realtek RTL8111/8168/8411, What are your ethernet assignments to the zones?

don’t forget to change back to DHCP quickly before it causes problems

Yes, I’ve come back to dynamic setting.

Red - Intel I350
Green - Intel I350

FYI: some modems (my Cisco 3010) reply with a status page on 192.168.100.1

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Hi Paul, I’m curious, on the firewall with it connected red via DHCP, if you run “ip link show” what does it say the MTU size is on the red interface?

edit: My modem status page -192.168.100.1 too (after changing to modem mode)

“ip link show”
red0: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
green0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000

I’m out of ideas on this one.
Maybe someone else knows something.

next minitests:

After installing version 125, 126, 129, 130, 141 - the same results - Download about 220-250Mb/s

On the IPfire machine, I was running Linux Mint Xfce Usb Live, instead of IPfire - dowload about 500Mb/s

3: red0: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000

At times, I use this script from Determine maximum MTU | Earl C. Ruby III for max mtu.

2 Likes

:thinking: Is it possible that IPfire ignores the MTU=1500 entry in the setup->networking…?

WebGUI Status–>Network (Other)->Routing table entries:
obraz

MTU 576? Could that explain half the dowload?

I don’t get the same output you show from Status > Network (Other) I do not get the mtu part, the line stops at metric 203. From your ipfire console, pls post output of “ip link show” (redact mac info)

ip link show

3: red0: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000

4: green0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000

edit
576 - I found this value in the file
/var/ipfire/dhcpc/dhcpcd-hooks/10-mtu
but I’m not a programmer to analyze it.

The 10-mtu hook is checking what the mtu value has been set at in other variables. The hook is checking if the mtu is greater than 576 and if not then it sets it at 576 as that is the lowest value that dhcpcd will work with.

https://www.speedguide.net/analyzer.php
this page detects such values

obraz
MSS: 536
MTU: 576
TCP Window: 262400 (not multiple of MSS)
RWIN Scaling: 8 bits (2^8=256)
Unscaled RWIN : 1025
Recommended RWINs: 65392, 130784, 261568, 523136, 1046272
BDP limit (200ms): 10496kbps (1312KBytes/s)
BDP limit (500ms): 4198kbps (525KBytes/s)
MTU Discovery: ON
TTL: 111
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

edit

For test, I insert #, in the file
/var/ipfire/dhcpc/dhcpcd.conf

# Respect the network MTU.
# option interface_mtu <------ here insert #

after insert # , this page detects such values

obraz
TCP options string: 020405b40103030801010402
MSS: 1460
MTU: 1500
TCP Window: 262656 (not multiple of MSS)
RWIN Scaling: 8 bits (2^8=256)
Unscaled RWIN : 1026
Recommended RWINs: 64240, 128480, 256960, 513920, 1027840
BDP limit (200ms): 10506kbps (1313KBytes/s)
BDP limit (500ms): 4202kbps (525KBytes/s)
MTU Discovery: ON
TTL: 111
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

edit
WebGUI Status–>Network (Other)->Routing table entries:
obraz

And, after insert # , download is about 500Mb/s :flushed:

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