You log in on your TV. Password works. You log in on your phone. Same password. Doesn't work. You reset your password. Now your TV doesn't work. Your phone works. Each device needs a different password. Your reseller's authentication is broken.
A British IPTV reseller whose passwords work on some devices but not others has an authentication system problem. Different devices send login requests in different formats. The reseller's server accepts some formats and rejects others. The password is the same. The server's response is different.
The British IPTV services with working authentication accept login requests consistently across all devices. One password works everywhere. The reseller who never tested across devices doesn't know that half your devices can't log in.
The IPTV reseller panel includes authentication settings. The reseller can configure which login formats the server accepts. The default settings sometimes miss formats. The reseller who doesn't adjust the defaults leaves some devices unable to authenticate.
The IPTV reseller UK operators who test on multiple devices would notice the inconsistency. They'd fix the authentication configuration. The resellers who only test on one device don't know that other devices fail.
Here's a specific scenario that makes no sense. Your TV streams fine. You try to watch on your phone. Login failed. You double check the password. Correct. You try again. Failed. You reset the password. Now your phone works. Your TV fails.
You're stuck with one device working at a time. You can't use both. The reseller's broken authentication system doesn't recognise the same credentials from different devices. You have to choose which device to use.
I've tested cross device authentication across dozens of resellers. Most work fine. The same password works everywhere. Some have inconsistent authentication. One device works. Another fails. The same credentials. Different results. The reseller's server configuration is the problem.
A consistent British IPTV reseller will have the same password work on all your devices. You can test this during your trial. Log in on your TV. Then log in on your phone using the same credentials. If either fails, authentication is broken.
The same principle applies to different apps on the same device. Some resellers' logins work in TiviMate but not in Smarters on the same device. The careful reseller tests across popular apps. Their login works everywhere.
A universally authenticating British IPTV service will let you use any device, any app, with one password. Test across your device collection before you commit. If any device fails, the reseller's authentication is incomplete.