Reading the manual for the PRIV I see standard WIFI options that allow the phone to connect to previously saved networks. Unless your home unit is weak or the channel it is using ( which can be changed) is also used by close WIFI routers such as neighbors you will get some level of interference. I had to change my own due to a neighbor adding multiple sub units with the same channel I was on with my router.
As for the ability to drop saved networks. this link for the phone shows how.
which I'm sure you already have. https://help.blackberry.com/en/priv/...r-Guide-en.pdf
You can also option the phone to not connect to WIFI when traveling.
Wi-Fi frequency band Tap to set the frequency band. When you set the band to 5.0 GHz, your device
connects to access points on the 5.0-GHz band only. When set to 2.4 GHz, your
device connects to access points on the 2.4-GHz band only. When set to
automatic, your device tries to connect to the band with the stronger signal