[SOLVED] Port Forwarding Help

I am setting up my local Blynk server (running on raspberry pi) to be accessible on the internet. I’ve got port forwarding working for everything except the app port - 8443.

7443 - good, can open the admin page
8441 & 8442 - seem good, I can telnet to those ports, haven’t sent blynk data yet…
8443 - telnet works, but no app data

Unrelated but working:
22 - SSH
3389 - Remote Desktop

Often times I will see the “Syncing Profile…” message. Other times, it says “Connecting…” but then it fails and says “Sorry, server can’t talk now. Try later.”

Any ideas?

Does everything work local? E.g. from within the LAN.

Have you generated some certificates? I’m pretty sure it doesn’t really matter, but it could be something. You could also check the blynk.log file to see if that gives any information. Also it’s possible to increase the log level with the server.properties file. You might try that to catch some more info. Generally, when everything else works, it could be something server-side, especially if Telnet works.

There is one last thing I’d mention and that would be your mobile internet provider. Because I’m on some sort of filtered network I can’t reach SSL ports on non-SSL ports. E.g. I can’t do SSL to anything other than port 443 and have to have valid certificates. You may look in to that too.

@cptnslick are you sure you are connecting to local server? Did you changed IP in app? Do you connect from local server? What IP address do you use in that case?

For the sake of helping someone else here are the answers to your questions:

Yes, everything works on the LAN. I keep looking at my router settings, but I can’t find anything wrong. Plus SSH and RDP are working with the same setup.

I haven’t tried the certs yet. I wouldn’t think they matter either, but I will try it.

I turned logging up to trace, but didn’t see any connection failing information.

Good thought on the mobile provider. That got me to troubleshoot the port again and I have a fix.

Port 443, per your suggestion, worked. That got me to try a few other ports and eventually I tried 8444 again. It worked this time, so I imagine I messed up switching the port the first time around.

One of these providers (I suspect it’s VZW) is blocking 8443 traffic:
My phone is AT&T
The internet for the Blynk server is VZW

Anyway, my problem was due to port block by one of my providers.


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Hi Dmitriy,
I had a port blocking issue with one of my internet providers. Thanks for the reply!

BTW - I really love Blynk. I will be happy to be a paying customer once you get to that point.

I’m glad you figured it out. As by magic, my provider finally unblocked their stuff, I have no idea why, but it suddenly works on my part, really weird. But of course it’s alway possible to run the server on regular ports or portmap a known port to an internal non-known port mode.