NSURLErrorDomain -1205 Error in companion app help please

Hi all you whiz kids, can anyone help with this issue.
I’m running HAOS with all latest updates installed. I have DuckDNS add-on and Nginx add-on as my remote access solution.
This has been working fine for the last 12+Months.
Now for some reason I get the below error when ever I connect from my iPhone (14PRO IOS 17Latest) using the companion app ‘Remotely’ (It works fine locally)

‘The server “Myname.duckdns.org” did not accept the certificate. NSURLErrorDomain - 1205’

My Mrs also has the companion app and her’s is working perfectly locally and remotely.
I have gone through everything I can think of and the only difference that I can find is she hasn’t yet upgraded to IOS 17 she is still on 16.
Anyone have a clue what this could be and how I can fix it…

Hi Mark,

I’m having the same issue but it affects both my and wife’s phones. I noticed it only occurs when the phone is on mobile data. In my case it works fine when the phone is connected to external wi-fi network - i.e. wi-fi at work or home network.

It was working fine for me for over a year and then suddenly stopped a couple of days ago. It looks like this affects both iOS and Android, as I checked with my friend who has Android and he’s experiencing the same issue.

I’ve done a little more checking after your comments and found the same as you. It does indeed affect both phones if we switch to mobile data, but still works fine on Wi-Fi away from home. Hopefully someone reading will have a solution soon :crossed_fingers:

+1 Me too.

Bit of an odd one. I similarly assumed it was somehow related to ios17 upgrade, but same situation on ios16 where it worked since that was released (O2 and 3 networks). Android user in house (3 network) has no such issues. Seems also to be location dependent for me, as occasionally I see my location has been correctly updated while I’m out and about with wifi off, but most of the times I try to use it I get the error.

EDIT: a small update. I noticed with Wireshark that nothing is even reaching the HA server. There is no request to be rejected. At that point I noticed I cant even access the duckdns website for the same reasons. Seems like some kind of network blocking maybe… Turning on cloudflare VPN ( app) works as a temporary solution.

I’m having the same problem. Like you this started happened recently and i noticed that it only happens when connected via mobile data.

I’m using O2 mobile and looking at the following post on their community page, it suggests that duckdns is being blocked.

[Blocked DNS server - O2 Community]

Looking at another post, this seems to have happened before and suggests that the domain is getting blocked because of malicious subdomains using duckdns.