For the Galaxy S9:
Has anyone else had an issue with the 4G connection not resolving after waking the phone via the power button?
I usually notice it after leaving a WiFi connection whereafter around 4-5min later I wake the phone and access the internet.
It will show up top that there is a 4G connection with full bars yet all of my apps will say there is no connection.
I will then pull the panel down and turn off then on the mobile internet. This usually fixes it but sometimes it takes multiple tries.
Do you think this is an issue with my phone or with the SIM?
It seems unrelated to WiFi. I think it is related solely with switching cell towers. If I am moving, e.g. via train, then it will lose the mobile internet connection after a bit (changing tower) and I will have to fix it using the above method.
Are you still having this issue? Is the software on your phone up to date? Go to Apps > Settings > About device > Software update. Also, let's try a soft reset on the phone. This will end all processes and give the phone a fresh start. To do this, press and hold the 'Power' and 'Volume Down' buttons until the phone restarts.
Basically it doesn't depend on telephone. Many of my friends have Sumsung S9 and everything is okay. May be it is problem with your provider. I had the same problem last year and only changing provider helped me. So I know the service were you can select the best one of the top UK companies. It is really useful. Also they can offer s enormous choice of different telephones or headphones for example. And there is a very helpful thing - you can get credit or return some money in cashback from your purchase. This means not only getting the right device, but also choosing the right network and tariff. Hope that it will help you in your situation. Here you will find all the information : https://usave.co.uk/mobile/