An ultrafast Tm-doped fiber laser operating at 1.7 μm is proposed based on nonlinear polarization rotation. This laser can generate multiple solitons and noise-like pulses. As the pump power increases to 270 mW, the stable fundamental mode-locked pulses are obtained by adjusting the intra-cavity polarization state with a corresponding central wavelength of 1785.88 nm, 3 dB bandwidth of 5.16 nm, and repetition frequency of 6.14 MHz. As the pump power increases to 290 mW, a multi-soliton bunch containing six pulses is observed, and the temporal spacing among pulses varies in the hundred-picosecond range. Moreover, the number of pulses in the single multi-soliton bunch increases with further increases to the pump power. As the pump power continues to increase, the multi-soliton bunch can switch to a special mode-locked state. Real-time spectrum based on a dispersive Fourier transform technique indicates that these special mode-locked pulses are noise-like pulses that are composed of noise pulses with random and varying intensities. Exploring the nonlinear evolution process and dynamic characteristics of mode-locked pulses after reaching a stable regime not only deepens the understanding of soliton dynamics but also contributes to the optimization design of 1.7 μm ultrafast fiber lasers, thereby promoting their development and application in various fields, including ultrafast optics, short-range remote sensing, and biology.