first check logs using

docker logs -f --tail 50 hassio_supervisor

check for output like

istant%2Fqemuarm-homeassistant&platform=linux%2Farm64: Internal Server Error ("Get "https://ghcr.io/v2/": dial tcp: lookup ghcr.io: no such host")
2025-03-31 15:48:12.252 WARNING (MainThread) Failed to install landingpage, retrying after 30sec
2025-03-31 15:48:42.255 INFO (MainThread) Downloading docker image ghcr.io/home-assistant/qemuarm-homeassistant with tag landingpage.
2025-03-31 15:48:42.272 ERROR (MainThread) Can't install ghcr.io/home-assistant/qemuarm-homeassistant:landingpage: 500 Server Error for http+docker://localhost/v1.45/images/create?tag=landingpage&fromImage=ghcr.io%2Fhome-assistant%2Fqemuarm-homeassistant&platform=linux%2Farm64: Internal Server Error ("Get "https://ghcr.io/v2/": dial tcp: lookup ghcr.io: no such host")
2025-03-31 15:48:42.272 WARNING (MainThread) Failed to install landingpage, retrying after 30sec

this is DNS error issue, and how to fix it?

type:

sudo rm /etc/resolv.conf
echo "nameserver 8.8.4.4" >> /etc/resolv.conf
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
systemctl enable systemd-resolved
systemctl restart systemd-resolved

wait a few minutes and check, if it still doesn't work then edit the /etc/resolv.conf file and add e.g. 8.8.8.8

it is a type of exchange of public keys and entering them into the Admin Key fields between nodes

Not working? remove (from admin perspective) managed node from node list, and wait for reappear, restart nodes.

Tip: You can set same Public key and Private key on each node (then Public Key an Admin Key will be same values, don't forget to copy prv key)

Tip: Admin key is public key of managed node (or node, admin node), it means "allow manage by admin that identifies by that public key"

Why These Changes Matter

Meshtastic has always been about open communication and the free exchange of data across a wide network of nodes. The ability to share GPS locations and other telemetry data via MQTT servers has been a cornerstone of the system’s functionality. However, with the new restrictions in place, the default MQTT server is no longer as versatile as it once was.

Under the zero-hop policy, the system’s capacity to relay information across multiple nodes has been severely limited. This, combined with the decision to restrict access to telemetry data, has made the default server less effective for users who previously depended on it for essential data. While it was initially believed that these restrictions would prevent users from subscribing to the general msh/# channel, which covers all data, it turns out that users can still subscribe to specific channels such as msh/DE/2/e/LongFast/ or msh/CZ/2/map/. Although this does limit the range of data available, it still allows for targeted listening.

Additionally, it is important to note that, as of now, the transmission of neighbour information or other data beyond a user's own data is no longer available. This change prevents users from conducting terrain analysis and utilizing telemetry for broader network management.

The Solution: Transition to Private Servers

Given these changes, it’s clear that the community must adapt by switching to private MQTT servers. By transitioning to private servers, users can regain control over their data and maintain the functionality that drew them to Meshtastic in the first place. This move also empowers the community to preserve the flexibility and openness that are core to the Meshtastic philosophy.

Final Thoughts

While the decisions by the administrators may have been made with the best intentions, the reality is that they have limited the utility of the default server. For those who value the ability to freely share and access telemetry data, switching to a private MQTT server is not just an option—it’s a necessity. Even though the ability to listen to broad channels has been restricted, the option to subscribe to specific channels still offers some functionality. As the community adapts to these changes, it’s important to stay informed and proactive in finding solutions that meet our collective needs.

Meshtastic alternative MQTT servers:

• Address: mqtt.meshnet.nl
• Username: boreft
• Password: meshboreft
• Website: meshnet.nl/nederland-map.html
• Primary target: Netherlands

• Address: mqtt.meshtastic.liamcottle.net
• Username: uplink
• Password: uplink
• Website: meshtastic.liamcottle.net
• Primary target: Global

• Address: loranet.pl
• Username: no username
• Password: no password
• Website: loranet.pl
• Primary target: Poland

1. Channels
   • LongFast
     • Uplink Enabled = ON
2. Device
   • Role = Client
   • NodeInfo broadcast interval = 3600
3. Position (for stationary device, mobile? jump to point 4.)
   • Position broadcast interval = 900
   • GPS Mode Enabled = False
   • Smart position enabled = False
   • Use fixed position = True
   • Latitude = type latitude for node location
   • Longitude = type longitude for node location
4. Position (for mobile device, stationary? jump to point 3.)
   • Position broadcast interval = 900
   • GPS Mode Enabled = True
   • Smart position enabled = True
   • Use fixed position = False
   • GPS update interval seconds = 120
5. LoRa
   • Use mode preset = True
   • Mode preset = LONG_FAST
   • Region (frequency plan) = EU_868 
   • Hop limit = 7
   • TX enabled = True
   • TX power = 27 
   • Frequency slot = 1
   • Override Duty Cycle = True
   • SX126X RX boosted gain = True
   • Ignore MQTT = True 
   • OK to MQTT = True (2.5.x, allow to spread telemetry accros other nodes )
6. MQTT
   • MQTT Enabled = True
   • JSON output enabled = True
   • Root topic = msh/pl (for Poland, or msg/cz for Czech, msg/EU_868 for EU etc.)
   • Map reporting = HIGH_PRECISION (or any other)
7. Store & Forward Config 
   • Store & Forward enabled = True 
   • Heartbeat = True
8. Telemetry
   • Environment metrics module enabled = True
   • (depends on module, Tbeam Supreme etc.) Air quality metrics module enabled = True
9. Neighbor Info Config
   • Neighbor info enabled = True
   • Update interval (seconds) = 600

All settings I haven't mentioned remain unchanged.

1. recompile firmware
2. open firmware/src/mesh/RadioInterface.cpp
3. find line that contain text "DEF(EU_868"
4. change to RDEF(EU_868, 869.4f, 869.65f, 100, 0, 30, false, false, false),
5. in same file look for

       if ((power == 0) || ((power + REGULATORY_GAIN_LORA > myRegion->powerLimit) && !devicestate.owner.is_licensed))
           power = myRegion->powerLimit - REGULATORY_GAIN_LORA;

6. replace this code with
   

   power = loraConfig.tx_power;

7. U can also tune chanutil limits inside airtime.h

8.     uint8_t max_channel_util_percent = 40;
       uint8_t polite_channel_util_percent = 25;
       uint8_t polite_duty_cycle_percent = 50; // half of Duty Cycle allowance is ok for metadata

I assume you know what you are doing and keep your radio space clean. In case of high radio noise, try to reduce the operating parameters.

how to compile using visual studio code: https://meshtastic.org/docs/development/firmware/build/