OT: Getting lot of "TCP Retransmission" when ssh to on machine

[Jon Ingason]

Hi, know that this not a Fedora problem. I have browsed the web without
getting answer the fit the problem I have.

I thing this has something to do with the network between to machines.
One, machine A, is in my study in my house the other, machine B, is in
my garage that i about 10 m away from house. Machine A is connected
directly the main Internet router. Between that router and machine B are
two extenders, C and D. Extender C is in extender mode, while D i meshed
to C. Machine B is directly connected to D.

The problem is that when I ssh from B to A everything is as it should
be. But if I ssh from A to B I get lot of "TCP Retransmission". The
connection from B to Internet is working excellent as well as for all
other devices connected to my network.

I just wonder if someone had some experience similar problems.

Machines A and B are x86_64 Fedora 26 kernel 4.13.11-200
Router is ASUS RT-N66R
Extenders are Strong Range Extender 1600

[George N. White III]

On 11 November 2017 at 11:28, Jon Ingason  wrote:
> Hi, know that this not a Fedora problem. I have browsed the web without
> getting answer the fit the problem I have.
>
> I thing this has something to do with the network between to machines.
> One, machine A, is in my study in my house the other, machine B, is in
> my garage that i about 10 m away from house. Machine A is connected
> directly the main Internet router.

By direct, do you mean using a cable or wifi?  Does A get an internet
address or
a private subnet address?
> Between that router and machine B are
> two extenders, C and D. Extender C is in extender mode, while D i meshed
> to C. Machine B is directly connected to D.
>
> The problem is that when I ssh from B to A everything is as it should
> be. But if I ssh from A to B I get lot of "TCP Retransmission". The
> connection from B to Internet is working excellent as well as for all
> other devices connected to my network.

If A has an internet address and B is on a private subnet using NAT,
A won't be able to connect to B, but B can connect to A.
> I just wonder if someone had some experience similar problems.
>
> Machines A and B are x86_64 Fedora 26 kernel 4.13.11-200
> Router is ASUS RT-N66R
> Extenders are Strong Range Extender 1600

That router supports multiple subnets with different access restrictions and
the range extender has "access point mode" which usually has NAT.  If
you don't need A or B to be reachable on the internet or separate subnets
with access restrictions, you should try to keep A and B on the same
(private)
subnet.
> t
> Jon Ingason
> _______________________________________________
> users mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]

[Jon Ingason]

Den 2017-11-12 kl. 00:53, skrev George N. White III:
> On 11 November 2017 at 11:28, Jon Ingason <[e-mail]
> > wrote:
> Hi, know that this not a Fedora problem. I have browsed the web without
> getting answer the fit the problem I have.
>
> I thing this has something to do with the network between to machines.
> One, machine A, is in my study in my house the other, machine B, is in
> my garage that i about 10 m away from house. Machine A is connected
> directly the main Internet router. 
>
>
> By direct, do you mean using a cable or wifi?  Does A get an internet
> address or
> a private subnet address?

I should be have more clearer in my description.
When I say connected directly I mean connected with cable.
Both A and B have static IP addresses on same pivate subnet (192.168.1.0/24)
> Between that router and machine B are
> two extenders, C and D. Extender C is in extender mode, while D i meshed
> to C. Machine B is directly connected to D.
>
> The problem is that when I ssh from B to A everything is as it should
> be. But if I ssh from A to B I get lot of "TCP Retransmission". The
> connection from B to Internet is working excellent as well as for all
> other devices connected to my network.
>
>
> If A has an internet address and B is on a private subnet using NAT,
> A won't be able to connect to B, but B can connect to A.

Se above and below.
> I just wonder if someone had some experience similar problems.
>
> Machines A and B are x86_64 Fedora 26 kernel 4.13.11-200
> Router is ASUS RT-N66R
> Extenders are Strong Range Extender 1600
> -
>
>
> That router supports multiple subnets with different access restrictions and
> the range extender has "access point mode" which usually has NAT.  If
> you don't need A or B to be reachable on the internet or separate subnets
> with access restrictions, you should try to keep A and B on the same
> (private)
> subnet.

The extender C is in extender mode.
The extender D is in mesh mode.

INTERNET ---- router <--WL--> C <--WL--> D
                |                        |
                A                        B

<--WL--> Wireless
----     Cable
|        Cable
> -- 
> George N. White III <[e-mail] >
> Head of St. Margarets Bay, Nova Scotia
>
> users mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]

[George N. White III]

On 12 November 2017 at 07:24, Jon Ingason  wrote:
> Den 2017-11-12 kl. 00:53, skrev George N. White III:
> > On 11 November 2017 at 11:28, Jon Ingason <[e-mail]
> > > wrote:
> > Hi, know that this not a Fedora problem. I have browsed the web
>
> without
> > getting answer the fit the problem I have.
> >
> > I thing this has something to do with the network between to
>
> machines.
> > One, machine A, is in my study in my house the other, machine B, is
>
> in
> > my garage that i about 10 m away from house. Machine A is connected
> > directly the main Internet router.

Now that we know both machines are on the same subnet, you are in for basic
network troubleshooting.  Unfortunately, the internet is saturated with
obsolete and
just plain wrong information.   You need to study man pages for the "ip"
and "ss".
https://devopscube.com/list-linux-networking-troubleshooting-and-commands-
beginners/
looks current.

https://unix.stackexchange.com/questions/50098/linux-
network-troubleshooting-and-debugging
is a helpful resource.

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/
1520/troubleshooting/guide/TrbleshtMesh.pdf
may be helpful

It would be a good idea to study and run the examples from the devops page
on your systems to see if any anomalies emerge.
> > By direct, do you mean using a cable or wifi?  Does A get an internet
> > address or
> > a private subnet address?
>
> I should be have more clearer in my description.
> When I say connected directly I mean connected with cable.
> Both A and B have static IP addresses on same pivate subnet (
> 192.168.1.0/24)
> > Between that router and machine B are
> > two extenders, C and D. Extender C is in extender mode, while D i
>
> meshed
> > to C. Machine B is directly connected to D.

Is B using wifi or cable?  Did you get your configuration from the vendors
docs?
Normally, mesh means 2 or more routers, but this is an area were vendors
use
proprietary algorithms, so you may need to ask the vendor for
recommendations.

I run a setup with two routers in "mesh" mode and a wifi to ethernet bridge
for
an office with multiple ethernet-connected systems, but I can also connect
directly with ethernet cable to either of the two wireless mesh nodes.  I
have
not seen asymmetries such as you encountered.  I wonder if C needs to use
"mesh" mode  -- the most common use case for extenders is for systems that
need internet access and don't run services like sshd for other systems.  I
have
seen reports of ssh problems using extenders with headless rPi boards.
> > The problem is that when I ssh from B to A everything is as it should
> > be. But if I ssh from A to B I get lot of "TCP Retransmission". The
> > connection from B to Internet is working excellent as well as for all
> > other devices connected to my network.
> >
> >
> > If A has an internet address and B is on a private subnet using NAT,
> > A won't be able to connect to B, but B can connect to A.
>
> Se above and below.
> > I just wonder if someone had some experience similar problems.
> >
> > Machines A and B are x86_64 Fedora 26 kernel 4.13.11-200
> > Router is ASUS RT-N66R
> > Extenders are Strong Range Extender 1600
> > -
> >
> >
> > That router supports multiple subnets with different access restrictions
>
> and
> > the range extender has "access point mode" which usually has NAT.  If
> > you don't need A or B to be reachable on the internet or separate subnets
> > with access restrictions, you should try to keep A and B on the same
> > (private)
> > subnet.
>
> The extender C is in extender mode.
> The extender D is in mesh mode.
>
> INTERNET ---- router <--WL--> C <--WL--> D
>                 |                        |
>                 A                        B
>
> <--WL--> Wireless
> ----     Cable
> |        Cable