In regards to Mobile Data >
As a process of elimination can you try your sim card in another phone and then see what happens @artbosque
This helps to rule out the phone or sim card.
Sim cards can be replaced via a sim swap carried out by the network.
Also try another sim in your phone and then see what happens.
If your phone is unlocked to all Network's then try another networks sim card i.e a pre pay / pay as you go one.
Check your network masts via any available network checker your network provides that checks local and surrounding Masts.
Mast congestion, weather, new buildings, tree foliage and population growth can all affect signal too.
In Settings > General Management > Reset > Reset Network Settings.
Check your phone via it's inbuilt diagnostic tool in the Samsung Members App.
A Samsung Experience Store or Samsung Service Centre can check your phone out too.
In regards to a Wi-Fi connection >
Forget the network settings in the phone and reset this Wi-Fi connection back up.
And in your home broadband router if you can split the frequencies to 2.4ghz and 5ghz and then set up the connection using one and then the other to see ehat the phone may prefer.
I wish you all the best. 
