I had the major update done at the dealer service in November,  my wifi kept disconnecting.  It solved most of my issues and I have been happy until this morning.  I had no wifi, so having been through this before I called AT&T to make sure there was no issue there, they had me pull over and change my wifi name, do a reset and keep the drivers door open.  It didn't work.  when I got home I called Ram Care, and spoke with Ruby.  She did some troubleshooting and said that I needed to go to the dealer for a master reset.  I really didn't want to do that again.  So I had her send me the reset directions again.  So here is what I did. 
I have the 8.4 uconnect system in my 2019 ram 1500 with navigation.
I had the vehicle running with the radio on.  I deleted my phone completely from the system.  Then I went in and under reset  in the menu I restored factory settings.  Then I held the two buttons inside the volume and tuner knobs for 10 seconds or so until the radio went into a reboot and shut off.  As soon as it went off i turned off the ignition, then opened my drivers door for a minute. 
Then I shut the door, powered the vehicle on.
Once the radio came back and the menu was all there I reconnected my phone to bluetooth, then went into the wifi menu and changed the wifi name and password. 
I then turned on the wifi hotspot in the truck and then connected my phone to the wifi, and did a speed test and it worked.  I made sure to use a new wifi name than any previous one I had. 
If it doesn't continue to work I will have to call back ramcare and set up a dealer appointment.  Im buying my truck off lease and I already have an extended maxx care warranty, and am still under factory warranty.  All the bases are covered. 
I hope the above information helps anyone on here who has an issue. 
Ram Care number is 866-932-3878  in case anyone needs it. 
2019 Ram Big Horn Crew Cab 5.7 Hemi.