Slow network response

Community
1

The network speed / response time is low
Connected to my server is a wireless router and two mesh points

Symptoms:

  • It takes several seconds to load a webpage or an app (e.g. Microsoft Teams)
  • When performing an internet speed test I get a low reading on the initial test (e.g. <50 Mbps) for download. Running a re-test immediately after I get readings of > 160Mbps. This is a consistent behavior.
    The speed test for upload always yields a result > 140Mbps

My config looks as follows:

  • I have a router with two NICs; one for LAN and the other for WAN (enp3s0).
    I run a pppoe client for the connection to the ISP amongst other with following settings: pppoe.parent enp3s0 ppp.mtu 1492.

  • /etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
#::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
10.5.2.1    home.wo-lar.com
10.5.2.1    wo-lar.com
10.5.2.1    home

/etc/resolv.conf

# Generated by NetworkManager
search wo-lar.com
nameserver 127.0.0.1

/etc/dhcp/dhcpd.conf

ddns-update-style none;
ignore client-updates;

lease-file-name "/var/lib/dhcpd/dhcpd.leases";
authoritative;

option domain-name                      "wo-lar.com";
default-lease-time                      86400;   # 24 hours
max-lease-time                          172800;  # 48 hours

subnet 10.5.2.0 netmask 255.255.255.0 {
        option routers                  10.5.2.1;
        option subnet-mask              255.255.255.0;
        option broadcast-address        10.5.2.1;
        option domain-name-servers      10.5.2.1;
        option ntp-servers              10.5.2.1;
        option netbios-name-servers     10.5.2.1;
        option netbios-node-type        8;
        range   10.5.2.101   10.5.2.200;
}
host amplifi {
        hardware ethernet 18:e8:29:c3:18:2d;
        fixed-address 10.5.2.2;
}
host HP_ENVY_PRINTER {
         hardware ethernet 6C:02:E0:9F:8B:64;
         fixed-address 10.5.2.10;

/etc/named.conf

acl internal-network {
        10.5.2.0/24;
};



options {
        listen-on port 53 { any; };
        listen-on-v6 port 53 { any; };
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        secroots-file   "/var/named/data/named.secroots";
        recursing-file  "/var/named/data/named.recursing";
        allow-query     { localhost; internal-network; };
        allow-transfer  { localhost; };

        recursion yes;

        dnssec-enable yes;
        dnssec-validation yes;

        managed-keys-directory "/var/named/dynamic";

        pid-file "/run/named/named.pid";
        session-keyfile "/run/named/session.key";

        /* https://fedoraproject.org/wiki/Changes/CryptoPolicy */
        include "/etc/crypto-policies/back-ends/bind.config";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

zone "wo-lar.com" IN {
        type master;
        file "data/master-wo-lar.com";
        allow-update { none; };
};
zone "2.5.10.in-addr.arpa" IN {
        type master;
        file "data/reverse-2.5.10.db";
        allow-update { none; };
};

Speed test from my server’s CLI yields the following:

Retrieving speedtest.net configuration...
Testing from Telefonica de Espana (83.51.253.96)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by CSUC (Barcelona) [0.15 km]: 10.326 ms
Testing download speed................................................................................
Download: 302.81 Mbit/s
Testing upload speed......................................................................................................
Upload: 302.07 Mbit/s

I found this article about TCP MSS Clamping in Firewalld
https://firewalld.org/2020/10/tcp-mss-clamp
Having set the mtu to 1492, would this still have an effect?

Thanks for your insight.

Wolfgang

2

Could you please clarify which device get slow response? The speedtest-cli on server is actually looking good.

3

Hello @zaffiro

thanks for your reply. I think I found the solution.
I set the maximum segment size used by a TCP session to ptmu and response time is much better now.

# firewall-cmd --permanent --direct --add-passthrough ipv4 -t mangle -I FORWARD -p tcp --syn -j TCPMSS --clamp-mss-to-pmtu

Wolfgang