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can't connect to server from outside LAN

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I'm running a Debian server from my home with a static IP address,
with ssh configured to use key-based authentication rather than
password-based.  As of a couple weeks ago, I have been unable to ssh to
my server from external locations.  When I ssh from a laptop connected
to the wireless network on the same router as my home server, I do
successfully connect to the server.  But when I ssh from an external
location, I get this error:

   OpenSSH_8.4p1 Debian-5+deb11u3, OpenSSL 1.1.1w  11 Sep 2023
   debug1: Reading configuration data /etc/ssh/ssh_config
   debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
   debug1: /etc/ssh/ssh_config line 21: Applying options for *
   debug2: resolve_canonicalize: hostname xxx.xxx.xxx.xxx is address
   debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/user/.ssh/known_hosts'
   debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/user/.ssh/known_hosts2'
   debug2: ssh_connect_direct
   debug1: Connecting to xxx.xxx.xxx.xxx [xxx.xxx.xxx.xxx] port 22.
   debug1: Connection established.
   debug1: identity file /home/user/.ssh/id_rsa type -1
   debug1: identity file /home/user/.ssh/id_rsa-cert type -1
   debug1: identity file /home/user/.ssh/id_dsa type -1
   debug1: identity file /home/user/.ssh/id_dsa-cert type -1
   debug1: identity file /home/user/.ssh/id_ecdsa type -1
   debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1
   debug1: identity file /home/user/.ssh/id_ecdsa_sk type -1
   debug1: identity file /home/user/.ssh/id_ecdsa_sk-cert type -1
   debug1: identity file /home/user/.ssh/id_ed25519 type -1
   debug1: identity file /home/user/.ssh/id_ed25519-cert type -1
   debug1: identity file /home/user/.ssh/id_ed25519_sk type -1
   debug1: identity file /home/user/.ssh/id_ed25519_sk-cert type -1
   debug1: identity file /home/user/.ssh/id_xmss type -1
   debug1: identity file /home/user/.ssh/id_xmss-cert type -1
   debug1: Local version string SSH-2.0-OpenSSH_8.4p1 Debian-5+deb11u3
   kex_exchange_identification: read: Connection timed out
   banner exchange: Connection to xxx.xxx.xxx.xxx port 22: Connection timed out

When I ping the server from external locations, I get 100% packet loss;
whereas when I ping the server from my local wireless network, there
is 0% packet loss.  (I do have nftables set to drop connections from
numerous IP addresses that have attempted hacks in the past; however,
the problem persists after flushing nftables, and at any rate, using
check-host.net and www.site24x7.com to ping my server from various
worldwide locations also results in 100% packet loss.)  Port 22 is open.
The package ufw is not installed on my server.

The apache2 Web server running on my home server is correctly hosting
my Web pages: from external locations, my Web page gmarks.org will
open in a Web browser (even though "ping -c 10 gmarks.org" shows 100%
packet loss).  Running "traceroute xxx.xxx.xxx.xxx" from external
locations reported four successful steps, not reaching my server IP,
followed by a series of "* * *" lines.

Running "sudo service sshd status" on my server shows ssh.service
is active and running.  Running "ip address show" on my server shows
nothing unusual.  I've restarted my router, and I've restarted my server;
neither helped.

The problem began a couple weeks ago; previously (and for many years)
I had been able to ssh to my server without issue.  The first time it
failed, I was using free wireless at an airport; I was able to ssh to my
server from the hotel that morning, and maybe, the first time I tried,
from the airport, but then subsequent ssh attempts from the airport
failed to connect.  I mention this only because nothing had changed in
my server's configuration when this problem began.

This is a real problem for me, as a lot of my work involves sending
files via scp between work and home.  Any suggestions about how to
troubleshoot and hopefully fix the problem will be greatly appreciated.

Best regards,
Greg Marks

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Thread

can't connect to server from outside LAN Greg Marks <gtmarks@gmail.com> - 2024-06-13 01:00 +0200
  Re: can't connect to server from outside LAN David Christensen <dpchrist@holgerdanske.com> - 2024-06-13 01:40 +0200
  Re: can't connect to server from outside LAN Tim Woodall <debianuser@woodall.me.uk> - 2024-06-13 02:30 +0200
  Re: can't connect to server from outside LAN Jeffrey Walton <noloader@gmail.com> - 2024-06-13 10:20 +0200
  Re: can't connect to server from outside LAN Monte Milanuk <memilanuk@hushmail.com> - 2024-06-14 04:10 +0200

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