I have a Samsung J3 and recently I notice some irregular 'blackouts' in the mobile connection. Suddenly, the connection is completely interrupted, then the connection is really slow (like 1.9 Mbps in the center of Geneva!), and then it works just fine (with download speeds well above 10 Mbps).
I restarted the phone, select 'Select automatically' in the available network settings, and talked to the provider. They admitted there was a network problem, but I am using it at two very different places.
So how to find out if it is my phone or the network?