Connection problem app-->Server LAN

Solved
1

Hello to everyone,

Using for a long time cloud Blynk Server, I decide to test a local Server installed in Raspberry Pi.
I have forward the nesesery ports 8441-8443 from my router to IP of local server (Pi).
I check that the ports are opened.
My app (android phone) connected ok to server using 4G or Wifi outside my network.
That means that I have incoming traffic routed ok to the server that runs blynk.
BUT, if I use the same LAN network with the Blynk Server (192.168.1.200) / android app (192.168.1.115) with Server Setting CUSTOM xx.xx.xx.xx (WAN) port 8443, it does not connected.
“Reconnecting to the server…” is the message of the app.
At the side of the server, from blynk.logs (trace level) there are NO new recordings when I try to connect to it.
Very strange.

Please advice
Regards
Nikos

2

Hello. In local network you have to connect to local IP.

3

Why?
Every time that I leave my local network I need to change the Server settings???
That is a bug or not (?).

Nikos

4

You need your router IP address (or external IP)

While on the same network as your local server, go to www.whatismyip.com

Then in Mobile app, connect to that ip…

If you have a static IP its easy… but if you have a dynamic IP from your internet provider then you will need to set up a dns service and assign a domain name.

For instance, my external address for my local server is ds.cust*s.co.nz:8442 (starred out for security)

5

My friend Jamin, we say the same thing.

I have dynamic ip address.
I have ddns service no-ip.
The problem is with no-ip domain name set on Server settings of the app connected to the same localnetwork.
With exactly the same setting of app using 4G, it is connected.

6

Oh so you’re saying if your on the local network… the ddns no-ip domain does not connect… but on another external network it connects fine with the same no-ip domain.

This sounds like an issue with your internal network blocking the loop back of the domain.

Have you checked router firewall of settings?

7

From the moment that I can connect usin 4G using no-ip domain that means that the internal network forward the trafic OK.

Android 4G external IP -->no-ip–>route–>ports 4881-4883 forward to LocalServer

8

but when you change to your local WIFI connection… you cannot connect?

9

Correctly

10

Open cmd prompt and type tracert external_domain

what is the result?

11

Tracing route to www.google.com [216.58.198.36]
over a maximum of 30 hops:

2 3 ms 3 ms 6 ms 192.168.2.1
3 26 ms 23 ms 25 ms loopback2004.med01.dsl.hol.gr
4 25 ms 35 ms 49 ms 62.38.140.35
5 32 ms 36 ms 32 ms 62.38.96.193
6 30 ms 31 ms 28 ms tengigaeth00-01-00-00.med00.ar.hol.gr [62.38.96.54]
7 31 ms 30 ms 29 ms gigaeth06-01.adr00.csw.hol.gr [62.138.97.42]
8 49 ms 26 ms 26 ms 79.140.91.12
9 44 ms 44 ms 44 ms xe2-2-0.palermo3.pal.seabone.net [195.22.28.103]
10 59 ms 60 ms 59 ms de-cix.pmov4.google.com [185.1.46.3]
11 60 ms 61 ms 64 ms 108.170.245.81
12 68 ms 81 ms 62 ms 216.239.48.231
13 73 ms 72 ms 73 ms mil04s04-in-f4.1e100.net [216.58.198.36]

Trace complete.

12

Ok looks like your router is blocking the external loop request.

Check your router firewall settings and unblock all outgoing connections.

13

Look up (update) tracert to google

14

Any other advice??

15

Dmitriy, if I am in the same local network why not using public IP to connect to Server.
Ports 8441-8442-8443 are forward to Server.

16

Sorry, we have other tasks to do. You have to resolve this by yourself.

17

mmm. That is a good idea!!!

18

Anyone else can help me…

19

Not sure if this is exactly what this post is about… but I utilize a program called BlueIris as my security & video surveillance system (probably more akin to a Blynk Local Server situation).

The app for that has both LAN and WAN input for login settings. It automatically uses local IP when in range of router WiFi and my DDNS.NET account when elsewhere.

But how would we resolve this ourselves?? I know I don’t understand how to modify Blynk’s login methodology :confused:

20

This is called NAT Loopback. And it has nothing to do with Blynk itself.