NESN is not available as a stand-alone subscription. It is only available to stream when you have a subscription to a paid service that carries NESN. YouTube TV was one such service until recently.
Per this Boston Globe page from October 2020:
"NESN is currently available on the streaming service fuboTV and AT&T NOW as well as cable providers. It is not available for streaming on Hulu or Sling TV."
AT&T NOW is not open to new subcribers, so look into fuboTV.
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