SmartSDR CAT will not connect to Radio on LAN

John K0TG

I am trying to use the 6600M at a different site than at home.  I am not using it remotely, I am on-site with the radio.  I have used this config before and it worked fine.

I have the 6600M and the PC connected to a router that is supplying DHCP.  The PC and the radio get addresses and I can ping the radio from the PC.

I just need SmartSDR CAT to connect to Writelog to control the radio.  So that is the only program I am opening.  When I open it it says no radios available.  I fired up SmartSDR and get the same.

I disabled the firewall on the PC for LAN connections and there is no firewall active.

Any ideas on this?  


Thanks, John  K0TG

Ted VE3TRQ

Since you can ping the radio, can you telnet to port 4992 on the radio? It should give you a dump of radio information if you connect (telnet radio_ip 4992). Also, if you "sniff" the network, do you see UDP broadcast packets on port 4992? These are what tell SSDR and CAT that the radio is there. Is there any possibility the router is blocking broadcasts?

John K0TG

John K0TG

I now have bypassed the router/switch completely.  I connected the PC to the radio directly.  I can ping the radio, but not connect to it.

73, John  K0TG

Bill - W9KKN

**** question, but are you running the same version of SmartCAT as the radio is running? 

John K0TG

Yep.  I made sure I did not goof that up.

John K0TG

I'm thinking it is a software issue on the PC side since I have the two directly connected.  So there is nothing between them blocking anything.  I also turned off the firewall on the PC on the LAN side.

Ted VE3TRQ

It would seem that if you can ping the radio, and telnet to it, there should be zero problems having SSDR or CAT talk to the radio. The only missing piece is the radio broadcast information, which is normally automatic from the radio once it has an IP address. If SSDR or CAT/DAX do not see that, they will not allow a connection, as it is done through the "Radio Picker" list, and that is populated from the radio UDP broadcasts. If you have the ability, verify the IP addresses assigned to the radio and the PC, and also if you can, sniff the network from the PC or another device on the LAN. What device are you using to run DHCP, and can you connect to that device to find out the status of devices given an IP address. I also assume the radio and PC are both set up to receive IP addresses via DHCP? Sorry about the more questions than answers.

Ted VE3TRQ

Another question: what do you mean by "telnet to the port and see the radio"? If you telnet to the radio TCP port, it will immediately dump a whole bunch of information about its state. If you don't see that, something is not right.

John K0TG

Hi Ted, no problem with the questions.  That is the process to fix things. 

I downloaded Wireshark hoping to see ethernet packets, but so far cannot get it to see the right interface.  

What I have done meanwhile is rolled back the PC a bit over a week.  There were some updates that came in.  That made no difference.  So I rolled it back to current. 

I lean more to the PC side of things since I have just a cable between the two now and still have the same issue. 

The radio is DHCP (not sure if you can set a static on it) and the PC is now set to a static address.  Since they are directly connected I need to set a static in the PC or it drops that config when the interface drops.

The radio seems to be able to keep the same address when I move the cable around as I am still able to ping it when directly connected to the address on the front screen.

Any thoughts as to what to look for on the PC side?  This was working at home a week ago.  I was out of town and just packed it up and came here.  I used this configuration before and it worked fine.

Thanks for your help.


73, John  K0TG

John K0TG

Just re-read this.  I did not answer that.  I did see the dump when I did a telnet to that address and port.

Ted VE3TRQ

I still think it is a better setup to use a router or level-3 switch in the middle to provide a DHCP address to both PC and radio, rather than allow the PC and radio to default to some link local "169." address :-) If you go to the 6600M front panel Menu / Network screen, what address(es) do you see there? You should see that the front panel and radio both have addresses. Taking the "Mask" value into account (it is a bit mask), the PC address must be in the same network. I am a Unix / Mac guy who tries his best to avoid Windows (unsuccesssfully :-), so normally do not use wireshark, but tcpdump instead. In any case, if you can watch the network LEDs, you should see periodic traffic from the radio sending its discovery packets. I'll see if I can come up with some easy-to-use Windows tool to just dump those for you - that appears to be what the PC is missing.

John K0TG

Hi Ted,

I am using 192.168.0.31 on the PC and the radio is 192.168.0.33. So no link local addresses here.  

I just got Wireshark running and I see a broadcast from the radio  source port 4992 dest port 4992.  So the radio is working fine.  It is a PC issue.  Maybe firewall?  But wireshark sees it, unless it looks right at the port before the firewall sees the packet.

Ted VE3TRQ

Well, John, you have verified all the things I would have suggested you do, so indeed it appears to be that the SSDR / CAT apps on the PC somehow or other are not seeing the broadcast. I have no deep Windows expertise to help further. Maybe a HelpDesk ticket is in order. One last thought: the 6600M consumes two IP addresses via DHCP, one for the radio and one for the front panel. What happens when the radio has an IP address and the front panel has none?

John K0TG

The front panel is 192.168.0.32.  So working ok.

Ted VE3TRQ

John, if you find a solution, please report back to this thread if you would. I plan on doing exactly what you are doing in the near future (operating my 6600M at a local event, using a Windows laptop), and would certainly love to know the cause of your problems. Ted VE3TRQ

John K0TG

Will do.

BTW, I just looked and the firewall is set to permit SmartSDR to communicate.  I may have to open a ticket on this one.  Thanks for the help.


John  K0TG

Ted VE3TRQ

John K0TG

Looked promising.  I do not see that service on the PC.  Windows 10.   I think I have to go to plan B (another radio for now).  Bummer.  

But thanks so much for the help.  Will post here what the resolution is.


John  K0TG

Ted VE3TRQ