How can I diagnose a network problem on my iPad?

"Check at Settings > General > VPN & Device Management as said by AlWeir not only for a VPN, but also any Developer Certificate that had been installed. I am sure you are aware that the EU allows other App Stores and side loaded apps from a website and the app is not available in the US, so that is the reason why I asked."

I've checked there. There's just one item listed: VPN - Not Connected. I understand something of the EU politics, yes, and your concern about sideloading. Can you tell me what the Cloud-and-down-arrow symbol means? Is it because I deleted it within the last thirty days and the info is backed up in the iCloud? I don't see how that could affect anything if so.

"In addition to the information provided, I would also recommend to power cycle both devices. Unplug the router for 30 seconds before plugging it back in, and also reboot your iPad."

I believe the iPad was rebooted when I upgraded it to 18.7.2. But I've just rebooted it again with no change in the problem. I'm reluctant to reboot my router since it affects everything else in my house and it doesn't seem likely to be the source of the problem since other devices (including an iPhone) can connect to the network OK.

Is there any way to ask the iPad to tell me more about what's going on when it tries to connect? A log for instance!

"How did you download the app?" From the App store! It's the first hit when I search for Fuuli. I'm in the UK; I don't know whether that makes a difference. Interestingly, the App store doesn't show Get or Open in the top-right corner for the app, it shows instead a cloud with a downwards-pointing arrow. I don't know what that means.

"I would delete the app." As I said, I have already done that.

"Verify Wi-Fi Connection:

Go to Settings > Wi-Fi.

Ensure the correct network has a blue checkmark next to it."

The blue check mark indicates that the iPad is connected to the network, AIUI. My whole problem is that I cannot connect to the network?

"If you see a message like "No Internet Connection" under the network name, tap the network's info button {i} in a circle).

Forget and Rejoin the Network

Go to Settings > Wi-Fi

Tap the info button {i}next to your network name.

Tap Forget This Network, and then confirm"

I've already said what message appears when I try to join the network. There's no text underneath any disconnected network; they just appear in a list.

When I click on the (i) button, I don't see anything about forgetting the network. I see "join This Network" in blue, and then Private Wi-Fi Address, which I've already set to Off, and the wi-fi address and three configuration items: IP - automatic, DNS - automatic, and proxy - off.

"I assume turning off Private Wifi Address did not help either? I just suggested that as a test because ISP's have been known to block access using the MAC address when P2P torrent activities have been detected as it violates the Terms of Use for many of them. I thought maybe with the MAC address change it would expose if that was the cause, but apparently not."

No it didn't help, I'm afraid. Good idea for the test though. I'm not sure how my ISP would know what devices I have connected to my network (I'd be a bit concerned if they did!) But I don't do torrenting in any case.

I'm beginning to think it must be something that app did. I'm in correspondence with the firm that supplied the device that required the app, so I'll press them a bit harder tomorrow. I just wished I could have collected some evidence that pointed the finger a bit more directly than a 'gut feeling'!

"Do have one installed, but it is just turned off. We have seen that the VPN still alters the network even when turned off and they actually need to be deleted."

No, I've never had a VPN on that device. IIRC I've never used a VPN except for a quick play with Tor when it first came out.

"Unfortunately it is common for the router to only have an issue with a single device where it is resolved with a reboot. I am not sure if that is the solution for you, but is the most basic troubleshooting step that works for many connection issues with a network. Another way to check if it is related to the router network is to take your iPad to another location and see if there is a problem connecting to that network. If you are able to connect to a different router, then you are going to have to look more closely at yours."

IMHO, it would be a pretty serious bug in a router if it was affected by a random device trying to log on. But as I say, the iPad has no problem connecting to the guest network on that router, so it's a problem only on the particular connection attempt. I'll try it in another location tomorrow though. There doesn't seem to be a log on my router.

Update: while I was typing I discovered there was an available update to the router software, so I upgraded it and that involved a reboot. But there's no change in the symptoms :(

"Are you using MAC filtering/Access Control on your router to specify devices that are allowed to connect to the network? That would explain why you are able to connect to the Guest Network."

No, I'm not. As its name hints, the guest network is where anybody is allowed to connect (there is a password to stop drive-by attempts though). And I'm not using filtering on my internal network either; I haven't found it necessary. I've turned off the private address toggle as suggested.