Direct TV Stream App Buffering

My DirecTV Stream has bad buffering issues. I have checked out my internet service and tests fine at almost 600mbs. Logged into modem and ran tests for db values and signal to noise ratios all checked fine. I un installed app and reinstalled it on a S21 Ultra and iPhone 13 Pro. I am casting to Chromecast from my phones. Did factory reset on Chromecast. Tried 2 other Chromecast devices. All have buffering issues. Been in contact with Technical support for 5 days in a row, they are clueless. Gives you a run around , sounds like they just read what's on a computer screen. They can't do real time on fly diagnostics. Anyone reading this if you Don't need Fox Regional Sports channels stay away from Direct TV Stream. The app is clunky, if you DVR a show it can't be streamed to you TV you have to watch it on your phone. The app makes for an unpleasant user experience as I came from YouTubeTV but they don't offer Regional Sports channels. Doesn't look like they are motivated to fix anything or upgrade anything. My YouTube, Netflix, FriendlyTV, Amazon, Tubi streaming and apps all work great.