I feel your pain as I'm also trying everything after signing up to this streaming service on a LG TV. The quality does go continuously dips down to 300 which is unwatchable. I also have fibre, watch Netflix and Prime with no problems. (I even double checked my Wifi channel for interfence which there is little or none)
I'm about to give up unless anyone has a solution?
Unfortunately, the LG app seems completely unusable.
I have an LG Bluray player with a Now TV app in it connected by cable to my router. I also have a Roku and a Now TV box. The Roku and Now TV box stream at 720p consistently over my broadband, the LG app produces a muddy unwatchable mess, and is using a very old interface that doesn't have the Kids channel group that was added a few years back.
I have two LG tv's.The one in the sitting room is hard wired and have never had any streaming issues at all.however the one in the bedroom is on wi-fi and only very rarely have i had any problems.I have always been surprised by the amount of comments for the lg app.maybe im just lucky.
Samd here. Been using the Now app on my LG for about two years viz TalkTalk broadband and have had hardly any issues with wifi or wired cinnections. Infact watching the second test as I type and first class picture.