How do I get two computers connected to the GTOCP4 WiFi to talk to each other?


Nick Iversen
 

I can get an iPad and a PC to both be simultaneously connected via WiFi DHCP to the GTOCP4. They can have IP addresses that differ by 1 in the last digit so are on the same network. But they can't talk to each other. They can't ping each other. Is there a way to get this to work?


mjb87@...
 
Edited

It's sounds like you are using the GTOCP4 as the access point here, rather than connecting the GTOCP4, your iPad and your PC all to the same LAN (as I do) which is another approach that may or may not be practical in your case, depending upon whether you have a LAN operating at your telescope site.

In your case, you might consider a VNC-type capability such as RealVNC or TeamViewer. I use RealVNC to communicate remotely between my iPad and PC. They don't even have to be on the same subnet or the same LAN if you are using a cloud-based solution. Of course, this assumes you have internet access at your site.

Some clarifying information would be helpful: Do you have internet access? Do yo have WiFI access to your LAN?


Jeffc
 

Interesting setup… which brings up a question ….
Does the CP4 / CP5 route between multiple clients on WiFi?

The fact that ping (icmp) doesn’t work might imply there is no IP level routing… tho icmp could be disabled on one of the devices.  (That said it would be easy to verify ping works with another WiFi router.)

I don’t use the WiFi on the CP5 but became curious on this topic as I do use a 12v WiFi router “in the field” between a laptop and the telescope computer (Remote Desktop).   (I attach to the CP5 using USB.).  I don’t use the upstream WAN port in the field.   The CP5 could be used for this, in theory.

So.. I took a look at the CP4 manual and it does seem to imply Access Point routing IS supported with caveats: 
a) no WAN routing and 
b) does not support large number of clients. 

Assuming routing is supported (for multiple clients on the CO4/5 WiFi) my only guess on this is there’s some config on the CP4/5 to setup routing .. or the default router/mask needs to be manually configured on the devices (Tho I thought DHCP normally does this.).   (My CP5 is currently packed , so I can’t easily experiment with this setup.)

-jeff
_._,_


Howard Hedlund
 

The GTOCP4/5 is not a network switch.  I believe that on a network, it is simply a terminal node.   I will confirm this later this afternoon with our engineer.


Christopher Erickson
 

A $50 access point will solve this problem.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Thu, Mar 10, 2022, 9:38 AM Howard Hedlund <howard@...> wrote:
The GTOCP4/5 is not a network switch.  I believe that on a network, it is simply a terminal node.   I will confirm this later this afternoon with our engineer.


Peter Nagy
 

If your telescope is located at your home property, you could connect CP4/5 to your home network using your existing router/access point? You can easily configure your CP4/5 via web access.

Peter


Nick Iversen
 

The GTOCP4 is a DHCP server. It allocates IP addresses 172.31.0.100 and 172.31.0.101 to two computers. It doesn't need to act as a switch or a router right?. The two computers should be able to talk to each other. But they can't. So RealVNC or TeamViewer won't work. It works on ethernet but not on WiFi.


 

>>> It doesn't need to act as a switch or a router right?.

I think it does. 

Serving up DHCP addresses and routing are two different functions. I suspect (but I don't know) the intent of the access point was to allow devices to communicate with the CP4. 

Brian

On Thu, Mar 10, 2022 at 2:45 PM Nick Iversen <inoddy@...> wrote:
The GTOCP4 is a DHCP server. It allocates IP addresses 172.31.0.100 and 172.31.0.101 to two computers. It doesn't need to act as a switch or a router right?. The two computers should be able to talk to each other. But they can't. So RealVNC or TeamViewer won't work. It works on ethernet but not on WiFi.



--
Brian 



Brian Valente


Jeffc
 



On Mar 10, 2022, at 2:51 PM, Brian Valente <bvalente@...> wrote:


>>> It doesn't need to act as a switch or a router right?.

I think it does. 

This is my understanding also.   

The WiFi is not point to point for clients (Eg just because they are in the same address range).   WiFi packets are received by the WiFi router then forwarded over wifi to the destination device.  

(If this weren’t the case then two WiFi devices could continue to talk to each other when outside of the AP WiFi range. Pretty sure it doesn’t work this way.)

So.. the question still remains … does the CP4/5 do WiFi routing?
(I did see Howard’s note, but haven’t seen a definitive follow up. 
Fwiw , I would suggest leaving the CP4/5 to tasks for which it is suited/designed for and WiFi routing to a purpose built cheap router.  This way if , for example, one needs to restart the CP4/5 WiFi is not interrupted.  But The AP team has better experience than myself in this area. )


Serving up DHCP addresses and routing are two different functions. I suspect (but I don't know) the intent of the access point was to allow devices to communicate with the CP4. 

Brian

On Thu, Mar 10, 2022 at 2:45 PM Nick Iversen <inoddy@...> wrote:
The GTOCP4 is a DHCP server. It allocates IP addresses 172.31.0.100 and 172.31.0.101 to two computers. It doesn't need to act as a switch or a router right?. The two computers should be able to talk to each other. But they can't. So RealVNC or TeamViewer won't work. It works on ethernet but not on WiFi.



--
Brian 



Brian Valente


Nick Iversen
 

OK I've got it now. The feature I am talking about is called "Client Isolation." On WiFi networks you can have Client Isolation which means that clients can't talk to each other. You can turn it off in your router. 

So it looks like the GTOCP4 has it turned on. My question then becomes - "Can I turn it off?" I'm guessing that the answer is no.

Looks like a separate router attached to either the ethernet port of the GTOCP4 or a WiFi bridge with Client Isolation turned off is the way to go.


ap@CaptivePhotons.com
 

On Thu, Mar 10, 2022 at 09:42 PM, Nick Iversen wrote:
Looks like a separate router attached to either the ethernet port of the GTOCP4 or a WiFi bridge with Client Isolation turned off is the way to go.
Yes.  

What I and a lot of people do is put in a small travel router.  I put mine on a separate subnet from the house; it forms an access point and hands out IP's to anything connecting (e.g. my cell phone or laptop), it has a wired connection to the CP4, and a wired connection to the NUC that lives on the tripod.  If it's at home it meshes with my home network and routes to it, and then has internet capability.  If i'm at a dark site where it is the only thing, then my laptop and phone can talk to the NUC and if needed each other as well. 

It's worth noting that some years ago you could do all this with a mini comptuer / NUC, but Microsoft changed things around where the wifi in most of them cannot form an access point, it can only join a wifi network, not be one. 

Some level of networking expertise can be needed to make it do all those things at once, but the key is getting a device that is really intended as a networking switch/router/AP.   There are a lot that are 12V and low power requirements.  And having a wired connection to the CP4 and your local NUC or whatever is more reliable than wifi. 

Linwood