Ditch powerline or get new ones

My primary question is: Should I do away with Powerline boxes and go with (say) a Ubiquiti UniFi product or something else. But is within the average geeks capabilities ( I can read a manual and google for Africa). The reason being, I am constantly having to sort out network outages and stuttering on playback.

My Draytek Vigor 130 Modem is in the garage (House is 2 level, 266 sq metres) and in bridge mode to a Edgerouter Lite 3.

I am on Spark VDSL. Fibre is July 2018 to June 2016 according to Chorus.

I believe I have 2 phase electricity (2 Meters outside). I am using Cat 5e and Cat 6 Patch cables.

The ethernet cable from the ERL3 goes to a Powerline D-Link DHP-601QV (single port, gigabit).

Throughout the house I have 5 others:

2 TP-Line TL-PA411

1 x D-Link DHP-P601QV (single port, gigabit into a 5 port hub)

2 x D-Link DHP-540 4 Port (gigabit)

Speedtest.net on an average day says: Ping: 18 - 22, Download: 36 - 40 Mbps, Upload: 8-10 Mbps

However, and more frequently, the Ping is OK and the Upload is say 7+, but the Download drops to 1 Mbps on a D-Link DHP-540 4 Port which is crucial to streaming from the Study to the rest of the house.

Thereafter, I am switching powerline boxes on and off (30 seconds to an hour) , swapping them out, re-booting PC's etc. Anything to get the speed back.

When I first got my TiVo about 9 years ago I swore I would replace wireless. Then again I had the bog standard ISP Modem Router.

I use an HG659 as a wireless AP, basically to serve my wireless Fitbit bathroom scales and mobile phone and a Spark HG630B AP to serve a mobile phone (since I had them spare).

Finally, I have found the TP-Link Powerline boxes to easily connect to the D-Link ones, rather than D-Link to D-Link.