  Massive stars that travel at supersonic speeds can create bow shocks as their
stellar winds interact with the surrounding interstellar medium. These bow
shocks - prominent sites for mechanical feedback of individual massive stars -
are predominantly observed in the infrared band. Confirmed high-energy emission
from stellar bow shocks has remained elusive and confirmed radio counterparts,
while rising in recent years, remain rare. Here, we present an in-depth
multi-wavelength exploration of the bow shock driven by LS 2355, focusing on
its non-thermal properties. Using the most-recent Fermi source catalogue, we
rule out its previously-proposed association with an unidentified $\gamma$-ray
source. Furthermore, we use deep ASKAP observations from the Rapid ASKAP
Continuum Survey and the Evolutionary Map of the Universe survey to identify a
non-thermal radio counterpart: the third spectrally confirmed non-thermal bow
shock counterpart after BD +43$^{\rm o}$ 3654 and BD +60$^{\rm o}$ 2522. We
finally use WISE IR data and Gaia to study the surrounding ISM and update the
motion of LS 2355. Specifically, we derive a substantially reduced stellar
velocity, $v_* = 7.0\pm2.5$ km/s, compared to previous estimates. The observed
non-thermal properties of the bow shock can be explained by an interaction
between the wind of LS 2355 and a dense HII region, at a magnetic field close
to the maximum magnetic field strength allowed by the compressibility of the
ISM. Similar to earlier works, we find that the thermal radio emission of the
shocked ISM is likely to be substantially suppressed for it to be consistent
with the observed radio spectrum.
