Millions of Canadians spent part of the weekend unplugged from the world wide web after technical issues at Rogers Communications (RCI  ) disrupted internet access for many areas of the country. The catastrophic outage has sent Rogers shares tumbling and prompted sharp criticisms of the company's monopolistic grip on Canada's telecom market.

Many web-based firms around the world watched the outage as it unfolded on Friday, with Cloudflare (NET  ) supplying a detailed explanation of the suspected cause in a blog post. The fault lay within routers at Rogers, which serve as the "bridge" connecting the various networks together that make up the wider internet. If that bridge should fail, as it did on Friday, it becomes impossible for networks to communicate with one another.

Canadians could not access the internet from phones and computers, while some reported being unable to make mobile or landline calls, including emergency services. Payment network Interac was disconnected for a time as well and would tell Reuters on Monday that the firm would be "adding a supplier (besides Rogers) to strengthen our existing network redundancy so Canadians can continue to rely on Interac daily."

Rogers restored service to much of Canada throughout the weekend, though as of Monday, several regions of Southern Canada are still experiencing outages, according to istheservicedowncanada.com.

The far-reaching consequences for much of Canada have triggered a wave of criticism of Rogers' monopolization of the country's telecom market and called into question a pending merger with Shaw Communications (SJR  ).

The merger was blocked by Canadian antitrust regulators earlier in the year, citing concerns of reducing competition in a market with some of the world's highest telecom rates. Just days before the outage, representatives from Rogers had met with Canadian regulators to discuss potentially un-blocking the merger. Many experts have already voiced skepticism that regulators would do so after such a catastrophic outage, however.

Beanfield, an independent network operator, tweeted: "A lack of competition and choice can lead to a building with the population of a small town going completely dark- cut off from all communications." The sentiment seemed to be shared by Industry Minister François-Philippe Champagne, who tweeted: "This unacceptable situation is why quality, diversity and reliability are key to our telecom network."

Similar arguments have been made in the United States against telecom and internet concentration, where antitrust complaints against major carriers are nothing new. Concentration of services has already led to similar incidents in the U.S., such as Amazon Web Services' (AMZN  ) west coast outage that took down entire sections of the U.S.-facing internet.

The last few days have been painful for Rogers Comms, with the firm losing 1.8% of its share value in after-hours trading. Market open on Monday sent shares even lower, Rogers stocks were 2.7% down an hour before close.