Syncthing "Failed to exchange Hello messages" in logs

[jano]

I am changing my server to use SWAG instead nginx which I did configure manually. This is working ok.
I also decided to replace syncthing from distro with LSIO syncthing container.

here is my config for syncthing

---
version: "2.1"
services:
  syncthing:
    image: lscr.io/linuxserver/syncthing
    container_name: syncthing
    hostname: skriatok #optional
    environment:
      - PUID=1000
      - PGID=984
      - TZ=Europe/Bratislava
    volumes:
      - /docker_volumes/syncthing/config:/config
      - /docker_volumes/syncthing/docs:/docs
      - /docker_volumes/syncthing/fotky:/fotky
      - /docker_volumes/syncthing/hudba:/hudba
    ports:
#      - 8384:8384
      - 22000:22000/tcp
      - 22000:22000/udp
      - 21027:21027/udp
    restart: unless-stopped

networks:
  default:
    name: kontainers
    external: true

this is swag

---
version: "2.1"
services:
  swag:
    image: lscr.io/linuxserver/swag
    container_name: swag
    cap_add:
      - NET_ADMIN
    environment:
      - PUID=1000
      - PGID=984
      - TZ=Europe/Bratislava
      - URL=skriatok.duckdns.org
      - SUBDOMAINS=wildcard
      - VALIDATION=duckdns
      - DUCKDNSTOKEN=xxxxxxxxxxxxxx
      - DOCKER_MODS=linuxserver/mods:swag-dashboard
    volumes:
      - /docker_volumes/swag:/config
    ports:
      - 443:443
      - 80:80 #optional
    restart: unless-stopped

networks:
  default:
    name: kontainers
    external: true

networks:

sudo docker network ls
NETWORK ID     NAME         DRIVER    SCOPE
0b7fd51b99f1   bridge       bridge    local
c8d1f8a36481   host         host      local
162775f03339   kontainers   bridge    local
49e54078bcf8   none         null      local

I can access web gui over subdomain.
I did setup folders and files did synced.
everything is working but in logs I see following messages:

[4K5MH] 2023/02/15 08:16:47 INFO: Failed to exchange Hello messages with QZA2RWM-key-xxx-xxx 
at 172.18.0.2:22000-192.168.75.152:40484/tcp-server/TLS1.3-TLS_AES_128_GCM_SHA256: 
write tcp 172.18.0.2:22000->192.168.75.152:40484: write: connection reset by peer

that makes me unhappy and I did check everything and can’t find solution.

docker network kontainers using this range 172.18.0.1/16
in actual situation syncthing container has 172.18.0.2 and swag has 172.18.0.4
192.168.75.0/24 is my local network and .152 is my laptop

I can log into containers and ping 9.9.9.9 without problems.

thank you for help

[jano]

I forgot to mention.

at begging there is OK message

Established secure connection to QZA2RWM-key-xxx
 at 172.18.0.2:22000-192.168.75.152:22000/tcp-client/TLS1.3-TLS_AES_128_GCM_SHA256

follow with

Device QZA2RWM-key-xxxx client is "syncthing v1.23.0" named "guido" 
at 172.18.0.2:22000-192.168.75.152:22000/tcp-client/TLS1.3-TLS_AES_128_GCM_SHA256

and that’s correct, and as I said, everything is working but I those fail message are still coming.

dont understand why server syncthing is trying to connect to some other port as 22000

I have another syncthing server on raspeberry running in same way {container from lsio behind swag}
and there are not those messages and my laptop is syncthing correctly.

[jano]

I delete container and remove config directory.
Then I did start new container.
I can access web gui and I see all default settings, so I enable only “local discovery”.

I am clicking “add remove device” and I can see all other devices which are running syncthing.

One is my laptop and another is my phone. {also my son and wife laptop}.

I did not add any device but already I can see fail message :

Failed to exchange Hello messages with QZA2RWM-xxxx 
at 172.18.0.2:22000-192.168.75.152:22000/tcp-server/TLS1.3-TLS_AES_128_GCM_SHA256: 
write tcp 172.18.0.2:22000->192.168.75.152:22000: write: connection reset by peer

that is my laptop, strange …

1. my laptop can connect with another syncthing devices.
2. looks that problem is with discovery

ok
I did pair my phone with server and it perfectly works.
photos from phone are synced with just created new syncthing container on server.

There is only one fail message which I did past few line before.
It is very strange, I have firewalld on laptop and syncthing is enabled.
I did enable LOG denied

firewall-cmd --get-log-denied
all

but dont see anything in journal

there is also nothing strange in syncthing log on laptop

[jano]

looks I did find a problem

on server I did replace syncthing from distro with syncthing from LSIO.container.

so new NODE is running on server.

on laptop I did keep old one and that was a source of “connection reset by peer” I guess.

I did turn on “connection” logging on laptop and there was a message for server IP “unexpected device id, expected XXX got YYY”.

Also in webgui, you need to click on device and in identification there was red message which I did overlook.

[jano]

so I did remove old node on laptop and fail message on server stop.