I tried the latest Ethernet over Power and it was abysmal. Wifi5 is good when close to the AP. At this point it's wiring for Cat6 in order to fully utilize my Gige from Comcast.
Cat3 doesn't meet the spec for GigE, but in short runs without a lot of crosstalk from dense wiring, it's likely to work and worth a try.
If you only have 2-pair wires in the wall, you can still likely run 100BaseTX, which is OK if not very exciting. At least you'd remove most of the jitter of wifi.
If you're in a rental, I dunno how the landlord would feel about you messing with the jacks, but it's undoable. If you were considering pulling new wire, you likely own.
I do own, so I don't mind running wires. Though I am being honest, back in 2003, I ran my own Ethernet in my apartment from the main room to my office.
I looked at thin ethernet to run under the carpet, but I am basically going from the main entrance (where the TV/Cable Modem reside) to the opposite end of the townhome, where my office is.
Prior to wires, I'm going to try the wifi6 mesh system from linksys. If I can get ~500-600mb/s to my office, that is a worth tradeoff.
- no conduit in the walls - no ethernet in the walls - coax to every room but it all terminates outside the house
which I'm sure meets most people's needs but was annoying for me. And it would've been so cheap to do it "right."
So I'm relegated to relying on the fact that I have very conveniently located unfinished half of basement and garage where I can do lots of cabling and just pop through the wall right at the end.
I just moved into a 100 year old house and my first home project was wiring the whole thing for ethernet, resulting in a funny situation where my house has gigabit ethernet cables running past the original knob and tube wiring in the attic.