Optical input is perfectly fine and always works all the time. HDMI ARC is technically better in terms of codecs it supports but real world difference is minimal of any for a soundbar, especially for streaming content, and it doesn’t necessarily work all the time. There is one HDMI port on most TVs designated the ARC. FWIW I have two soundbars (Bluesound) that have both HDMI and optical inputs, and use the optical on both. Some soundbars have HDMI passthrough, these are much less common but the soundbar has the input devices attached, can switch between them and outputs video to the TV.