Can't play anything larger than 2gb smoothly.

Hardwired 4K Max firestick with 300mbps internet connection and real dbird.

Samsung 4k QE75

Was working perfectly until 3/4 weeks ago, now glitchy when playing any file over a couple of gb. Working perfectly fine on my phone over wifi streaming 80gb plus files.

Tried Firestick on another TV and network. Some issue.

Tried external player and change streamio settings. Same issue.

Anyone have any thoughts or experiencing the same issue?

Cheers,