I am not very knowledgeable about networking, so I am easily stymied. I used Rob Lancaster's installation script for my Ubuntu mini-pc installation. At home Ubuntu connects to my wifi and I connect from windows using VNC Viewer.

Away from home, Ubuntu uses that same wifi to establish a hotspot. That works, and I can connect my laptop to the hotspot. However, I cannot get a VNC connection to work (have tried multiple viewers).

This all worked correctly last fall - same laptop, same mini-pc and I am obviously unsure what exactly changed in the interim. The windows laptop, when connected to the Beelink's wifi hotspot, does not have an IP address. I'm guessing this has something to do with the problem. How can I determine if Ubuntu is configured to act as DHCP server? "Connection Information" for the hotspot shows 10.42.0.1. In the Settings for the hotspot, IPv4 Settings tab, all the fields are blank.

Thanks in advance for any pointers to the right direction.

Let me sum up:

1. Home: Your Windows PC and your Ubuntu mini-pc shares the same network (home network) and you have no issue.

2. Remote: On a remote location, the Ubuntu mini-pc creates a WiFi Hotspot, which you Windows PC connects to and you have no issue.

3. Work: (This is where I got lost). Your Ubuntu mini-pc is at home connected to your home network (via Ethernet? cause your wifi card acts like a hotspot at the moment), and you try to connect through your Windows PC from your workplace ?

[edit: quotes do not appear - reformatting my post]

Hi Euripides, thanks for thinking about this.

"1. Home: Your Windows PC and your Ubuntu mini-pc shares the same network (home network) and you have no issue."
This is correct. The ubuntu mini-pc uses its highest-priority wifi connection to connect to my home wifi network. It obtains an ip address, can access the outside world and I can use VNC Viewer to remote-control it by connecting to BEELINK::5901. No change here, this has always worked.

"2. Remote: On a remote location, the Ubuntu mini-pc creates a WiFi Hotspot, which you Windows PC connects to and you have no issue."
This is only partly correct. When I turn off my home wifi, ubuntu correctly creates a wifi hotspot according to its second-priority connection setting. On my windows laptop (and also on a windows desktop pc) I see the hotspot and can connect to it. The windows box says "Connected", but does not obtain an ip address from ubuntu. On the ubuntu machine, arp -a shows no connected devices.



"3. Work: (This is where I got lost). Your Ubuntu mini-pc is at home connected to your home network (via Ethernet? cause your wifi card acts like a hotspot at the moment), and you try to connect through your Windows PC from your workplace ?"

Sorry for being unclear. There is no 3rd situation like this, only #1 and #2.

Cheers,
Ron

I think i got it: The issue is that while the hotspot connection seems to be working (you can actually connect through it) you do not have an IP for the connected device.

Ok so, first things first:
- Are you fully updated on your mini PC?
- The same happen for any device? If you try through your phone?
- Did you try to create a new hot spot?

Yes, we appear to be on the same page now.

The mini-pc is fully updated
I have tried both a laptop and a desktop windows pc, neither obtains an ip address, neither appear in the arp -a device list
I just created a new hotspot - same behavior

I've been googling away. Unfortunately my linux skills consist primarily of hoping it all works without much intervention...

It appears that ubuntu does not arrive with a DHCP server, so one must be installed separately. Apparently the most common is isc, though isc says it is no longer maintained and one should use kea. kea looks way more complicated to configure, but it that's what is need I shall have a go at it.

It is still a total mystery to me how it ever worked in the first place (and why it stopped working), if it is indeed true that there is no built-in DHCP service. I have searched through Rob Lancaster's astropi3 script for ubuntu (which I used for my installation), and find nothing about installing any of the DHCP servers or configuring DHCP.

Update: My current theory is that there is firewall setting or configuration getting in the way.

With the mini-pc connected to my home network and the firewall active, VNCViewer works fine from either my laptop or desktop.
With the mini-pc running its hotspot and the firewall active, I cannot connect reliably. I have ports 5900, 5901 and 5902 open for tcp. Some times VNCViewer will connect and show the ubuntu desktop, but there is no mouse or keyboard control from the viewer.

So I can work around by disabling the firewall when I go out to remote image.