Buffering is usually a bandwidth or Wi-Fi issue, not the app alone. For ErsatzTV streaming:

• HD: aim for ~15 Mbps stable
• 4K: aim for ~30 Mbps or higher
• Prefer ethernet or strong 5 GHz Wi-Fi near the TV

Close bandwidth-heavy downloads while watching live sports. If streams still stutter, restart the player and test another channel quality profile.