I have the galaxy S9.
I have secure Wi-Fi listed in Wi-Fi settings advanced settings. It is not activated by default. In order to use it you first have to agree to the terms and conditions and then activate it. If you don't want to pay for its premium service you get 250 mb of free bandwidth each month.
I chose not to use it. I don't have any pop-up notifications associated with it.
You might try going into settings /Apps/ select Secure Wi-Fi / tap on the storage entry and clear the cache and data. Tap the back key and find the notifications entry on the list and turn off the notifications.
It's runs at startup but only holds about 12 mb of memory. It's just another app or service option on my phone that I don't use but a lot of people use every day.
It's good to hear that thanks. If it starts again let me know. As you mentioned constant notifications or advertising from apps I don't use are extremely annoying and I have a really low tolerance same as you.
Have a good one,
This also worked for me, S9+ with Danish Telia operator. Also important is to force stop the app.
All the junk Samsung phones have in them (not only this , but also junk like, for me , Bixby, kept me away from them between the first Galaxy S phone and this company owned S9+ I have. @samsung @@ STOP filling up your phones with Junk!