WiFi Disconnects When Ethernet Cable Disconnected

I've got an odd one for you guys. So I've got a C-7 hub hooked up in an office building and it's been working on the LAN for several weeks. Ideally I'd like to be able to connect the hub to the WiFi, so I bought the recommended OTG+ Power Cable and TP-Link Long Range USB Adapter and followed the directions to hook it up and voila! The hub found the WiFi network I wanted to connect to, got an IP, and I was on my way. I shut down Ethernet and moved the hub to another location (a few feet away) and fired it back up. Light turned green and I figured all was well.

However, the hub won't stay connected to the wireless, so far as I can tell. The APs can see it but it never responds to the IP address it purports to have (so I never could get the hub to load in a web browser either).

I disconnected the hub from the WiFi adapter and plugged it back into Ethernet and went back into the setup and all looked good. So out of curiosity, I thought I would plug the WiFi adapter back up and see if it behaved better in the location where I had set it up originally. When the hub booted, it reconnected to the wireless and 'lo and behold, the hub replied to pings on the WiFi address consistently. So I unplugged the ethernet cable and returned to my running ping and it had stopped responding. Plugging the ethernet back in has it responding again.

2023-02-24 14_31_44-Command Prompt

I've never seen anything like it. The hub has two addresses (wired and wireless) but both stop working when Ethernet is unplugged.

What am I missing here?

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If the IP you are trying was the IP when the hub was on ethernet, that's your problem right there. You will need to reserve a new IP with WIFI dongles MAC address and use that IP to get to the hub.

It's not. The WiFi got a separate IP (yes while it was on ethernet but it was from the WiFi AP) and it won't respond on that IP when the Ethernet is shut down. Are you saying I should do an IP reservation, even given that fact?

Yes you should always reserve IPs to the MAC for all IOT devices.

The hub I use on WIFI has 2 IPs reserved for it, one for the WIFI dongle and one for Ethernet in case I need to reconnect it for some reason.

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OK I can do that, but I still don't understand why the WiFi did what it did. I can see the two IPs that the hub has (wired and wireless - neither changed) but the WiFi IP stops responding the minute the ethernet is disconnected.

I'm just relating my experience, might not be the same problem at all but it's looking a lot similar to what I experienced a few months ago.

If that does not work/help, maybe someone else will chime in with other info.

So I went ahead and did that and reserved 2 IPs right next to each other ( for the ethernet MAC and for the WiFi MAC). I shut down ethernet and ran a ping and the hub was still replying on both IPs so I assume that was just some weird binding through the WiFI adapter. But clearly it was working. However, I just unplugged and replugged it and now it's gone offline again. Have I done something incorrectly with the hub so that it does not maintain WiFi after a reboot?

After some tinkering, I think I finally got it. The ethernet is unplugged and it is replying on the reserved IP address for WiFi. Thank you for the suggestion!

For future prosperity, what do you think "fixed" it?

The DHCP reservation finally being right. For some reason the MAC that shows up on the DHCP server is really long so I had to do an โ€œautomaticโ€ reservation via the DHCP scope and then copy the MAC entry from it so that it got the IP I wanted. Then I shut down the hub and moved it and it fired right up perfectly.