Done many server 2016 installs, never seen a problem like that. Is windows firewall maybe a factor?
howz the setup of your solarwinds main poller and additonal to the DB? Is it across WAN?
do also verify if the SQL port is having any issues from firewall perspective... if its happening frequently then u can observe the pattern in terms of when its occuring and getting restored..
Worth to check if there is any issue with permissions or any configuration at SQL level.... last option i would suggest is- Reboot your SQL server...