I have same issue, suddenly it started to show "Authentication failed", My donation is iptv66 I just put new URL but it is still showing same error. I did: kodi uninstall/install, ip reset, mac clean and rewrite. Below you can see my log, I scrubbed some parts related to my subscription :
15:03:39.804 T:14888 DEBUG: AddOnLog: Stalker Client: ADDON_Create: Creating the Stalker Client PVR Add-on
15:03:39.804 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'active_portal'
15:03:39.805 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'connection_timeout'
15:03:39.807 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'mac_0'
15:03:39.808 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'server_0'
15:03:39.810 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'time_zone_0'
15:03:39.811 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'login_0'
15:03:39.812 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'password_0'
15:03:39.814 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'guide_preference_0'
15:03:39.815 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'guide_cache_0'
15:03:39.816 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'guide_cache_hours_0'
15:03:39.818 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'xmltv_scope_0'
15:03:39.819 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'xmltv_url_0'
15:03:39.820 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'token_0'
15:03:39.822 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'serial_number_0'
15:03:39.823 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'device_id_0'
15:03:39.824 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'device_id2_0'
15:03:39.826 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::GetAddonSetting - add-on 'Stalker Client' requests setting 'signature_0'
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: active_portal=0
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: connection_timeout=30
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: mac=00:1A:78:zz:ZZ:ZZ
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: server=http://s1.iptv66.tv/c/
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: timeZone=Europe/Kiev
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: login=xxxxxxxxxxxxxx
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: password=YYYYYYYYYYYYYY
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: guidePreference=3
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: guideCache=1
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: guideCacheHours=24
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: xmltvScope=0
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: xmltvPath=bbbbbbbbbbbbbbbbbbbbbbbbbb
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: token=34223425567
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: serialNumber=1234567898765
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: deviceId=9876543210987
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: deviceId2=23423423543
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: signature=34578992
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: SData::ReloadSettings
15:03:39.827 T:14888 DEBUG: AddOnLog: Stalker Client: SData::LoadCache
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::SetEndpoint
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::SetEndpoint: m_basePath=http://s1.iptv66.tv/
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::SetEndpoint: m_endpoint=http://s1.iptv66.tv/server/load.php
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::SetEndpoint: m_referer=http://s1.iptv66.tv/c/
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SData::Authenticate
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SessionManager::GetProfile
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::STBGetProfile
15:03:39.828 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::StalkerCall
15:03:39.828 T:14888 DEBUG: CFileCache::Open - opening <server/load.php> using cache
15:03:39.832 T:14888 DEBUG: CurlFile:
arseAndCorrectUrl() adding custom header option 'Authorization: ***********'
15:03:39.832 T:14888 DEBUG: CurlFile:
arseAndCorrectUrl() ignoring header option 'X-User-Agent: Model: MAG250; Link: WiFi'
15:03:39.832 T:14888 DEBUG: CurlFile::Open(14BFE000)
http://s1.iptv66.tv/server/load.php?type=stb.......................................
15:03:39.832 T:14888 INFO: XCURL:
llLibCurlGlobal::easy_aquire - Created session to
http://s1.iptv66.tv
15:03:40.137 T:5736 DEBUG: Thread FileCache start, auto delete: false
15:03:40.137 T:5736 INFO: CFileCache:
rocess - Source read didn't return any data! Hit eof(?)
15:03:40.187 T:5736 DEBUG: Thread FileCache 5736 terminating
15:03:40.187 T:14888 DEBUG: AddOnLog: Stalker Client: HTTPSocket::Execute:
15:03:40.187 T:14888 ERROR: AddOnLog: Stalker Client: SC::SAPI::StalkerCall: parsing failed
15:03:40.187 T:14888 ERROR: AddOnLog: Stalker Client: SC::SessionManager::GetProfile: STBGetProfile failed
15:03:40.187 T:14888 DEBUG: CAddonCallbacksAddon - V1::KodiAPI::AddOn::CAddonCallbacksAddon::QueueNotification - Stalker Client - Error Message : 'Authentication failed. Retrying.'
15:03:45.187 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SessionManager::GetProfile
15:03:45.187 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::STBGetProfile
15:03:45.187 T:14888 DEBUG: AddOnLog: Stalker Client: SC::SAPI::StalkerCall
15:03:45.188 T:14888 DEBUG: CFileCache::Open - opening <server/load.php> using cache
15:03:45.191 T:14888 DEBUG: CurlFile:
arseAndCorrectUrl() adding custom header option 'Authorization: ***********'
15:03:45.191 T:14888 DEBUG: CurlFile:
arseAndCorrectUrl() ignoring header option 'X-User-Agent: Model: MAG250; Link: WiFi'
15:03:45.191 T:14888 DEBUG: CurlFile::Open(17859E88)
http://s1.iptv66.tv/server/load.php?type=stb......................................
15:03:45.468 T:12524 DEBUG: Thread FileCache start, auto delete: false