According to that log, you have several problems.
1) You're streaming over Wifi. NEVER stream over Wifi. It's designed for lightweight content consumption on mobile devices. Any streaming rig should have a network cable run to it.
2) You're trying to stream 1080p60 at 2500kbps on x264 Veryfast. 1080p60 wants 12mbps (12000kbps) on average to look decent. You either need to raise your bitrate by a LOT, or downscale and run at a lower framerate to fit within that bandwidth budget. This is your big issue about it looking awful, compounded by streaming to YouTube who re-encode everything they receive. For 2500kbps, you'll want to run at most 720p30.
3) x264 Veryfast is workable, but you have a GTX 1060. It supports NVENC, and the 10-series generally encodes at a quality level around x264 Fast (which is better). It's also a separate core on the GPU and will use no game-rendering resources (as long as you don't use the Max Quality preset, and have Lookahead and Psychovisual Tuning turned off). Swapping to NVENC is strongly advised.