That depends mostly on what your upstream speed is rather than the overhead of VPN. Do you have a symmetric broadband connection (down and up speeds are the same)?
Further, if you dad is using Wi-fi, you may have an uphill battle sustaining the bandwidth on his end.
My connection is supposed to be 1 Gbps up/down no data cap for $85/mo. I was paying Windstream $140/mo for a dual DSL line G Bonded modem including land line that gave us only a max of 35 Mbps down/1.5 Mbps up, due to poor quality phone lines. NO Plex upload with that speed.
His wifi will stream 4K movies off my VUDU account, he has a Cox cable modem @15Mbps, my Plex movies are all 1080p so it should be OK. If no I'll buy him more speed. My ExpressVPN speeds are generally between 23 to 40 Mbps down and around 80 Mbps up so I should be good. Try'd Nord for a day, got a refund, they were slower and had a klunky interface.
Installed my CAT 7 cables last night, same 95 Mbps down 300 Mbps up.
Figured out the ethernet card in my new (last year) Dell Inspiron 3780 is only 10/100 ARGH!! So I ordered a USB 3.0 to ethernet adapter.
My Netgear R9000 router has Plex built in, with a WD Easystore 8 TB drive loaded with 6.5 TB of backup to my Synology 918+ with 4X8 TB drives. I run 2 8TB Easystore USB 3.0 backup drives, one on the router and the other on the 918+. Don't want to expose the 918+ outside the home network.
Should work ok, I just have to wait for the CV-19 lockdown to end at his facility so I can set it up at his end.
I'm still not sure about my fiber connection, but will wait till Thur. when the adapter arrives before I bug customer service. The installer knew even less about networking than I do. Scary, he's a former Dish Network installer, so a little bit out of his depth. Really nice kid though, he'll learn. I'd rather have nice and eager to please than "know it all A** H*le".