what is a major benefit stp provides that utp does not?

Error: Message: unknown error: net::ERR_PROXY_CONNECTION_FAILED (Session info: chrome=135.0.7049.114) Stacktrace: #0 0x5568bd26a75a #1 0x5568bcd1d4b0 #2 0x5568bcd14593 #3 0x5568bcd04c69 #4 0x5568bcd0696d #5 0x5568bcd04ffe #6 0x5568bcd0499e #7 0x5568bcd0464f #8 0x5568bcd024cf #9 0x5568bcd02c8a #10 0x5568bcd20949 #11 0x5568bcdbb1f5 #12 0x5568bcd94592 #13 0x5568bcdba5e0 #14 0x5568bcd94363 #15 0x5568bcd60d63 #16 0x5568bcd619c1 #17 0x5568bd22fa6b #18 0x5568bd233951 #19 0x5568bd217b62 #20 0x5568bd2344c4 #21 0x5568bd1fc13f #22 0x5568bd2586f8 #23 0x5568bd2588d6 #24 0x5568bd2695a6 #25 0x7f720d302ac3