Previously i state will test powerline to somebody here, sorry forgot who. Here's some result:
Internet speed: 500Mbps
Software: Speedtest (Windows 10 app) using TIME server.
Router: Tplink C1200
Powerline adapter: Aztech 500Mbps model.
Test done from Bedroom:
1. Using 1Gbps USB 3.0 to Gigabit adapter - 115Mbps download, 12x Mbps upload. Latency 6 or 7.
2. Using my laptop built in Wifi N - slow until i don't want to say.
3. Using T9UH USB 3.0 adapter - 300Mbps download, 250 to 300 Mbps upload. Latency 2 to 3.
Test done next to router: (test is running while wife watching kdrama on a htpc connected via wired - can't tell wife to switch off kdrama...

)
1. Using T9UH USB 3.0 adapter - 353Mbps Down / 341 Mbps Up. Latency 3. (TIME server)
2. Using T9UH USB 3.0 adapter - 367Mbps Down / 89 Mbps Up. Latency 4. (MacroLynx server)
3. Using T9UH USB 3.0 adapter - 342Mbps Down / 298 Mbps Up. Latency 5. (DIGI server)
4. Using T9UH USB 3.0 adapter - 357Mbps Down / 383 Mbps Up. Latency 7. (TELEKOM server)
Hope these result is helpful.
My conclusion: Powerline adapter is only good up to 100Mbps internet. If you have > 100Mbps, please use Wifi AC with a good wifi adapter.

Knew it tbh, so not a surprise.