I do 100+ nights with Marriott a year and it's rare to have one with Internet so dysfunctional as this one. Really would not work, period. They admitted this was a common issue but didn't seem to know how to rectify.
The other thing I found shocking was the lack of mask-wearing despite it — supposedly — being a Marriott brand standard.
Anyway, do you need to stay in a Marriott in Helena? Stay at the Delta or the Residence Inn. Do you need to stay at a Fairfield in Montana? Stay at the one in Butte or Missoula or Bilings. Do you need to stay at a limited-service chain hotel in Helena? Try the Holiday Inn Express. That was where I ended up after leaving this hotel early.
Bottom line, this one should probably be de-flagged, sadly.