If the Netflix video you watch via a Comcast connection seems slow and unreliable, you are not alone.

Other Comcast customers in the Twin Cities and around the country said they have been frustrated with poor-quality Netflix video, frequent streaming hiccups and other issues that, in certain cases, have persisted for months.

These customers say other video-streaming services, such as Hulu Plus and YouTube, are not affected in this way.

The Internet is full of reports of degraded Netflix service, typically delivered by Comcast or Verizon’s fiber-optic service (or FiOS).

And while the cause of such subpar Netflix service is unclear, some suspect that “throttling” — deliberate degradation of the signal — is partly to blame.

Verizon has told news outlets that it is not intentionally interfering with Netflix streaming in any way. Comcast declined to comment for this report.

“Netflix has been horrible in 55116, and I have Comcast,” Stephen Schreiber said. The 55116 ZIP code includes a portion of St. Paul near Fort Snelling.

“Netflix is BY FAR the worst on my Sony Bravia” TV, Bob Collins, who works at Minnesota Public Radio, said in a Twitter post. “Hulu Plus, Amazon Prime, everything else is just fine.”

Anthony Domanico, a St. Paul-based technology journalist, also sees better performance with Amazon streaming than with Netflix, which he said is plagued with a less-than-optimal video resolution and frequent pauses to reconnect with Netflix’s servers. This problem has persisted since November, he said.

“Amazon streams perfectly in 1080p” resolution, said Domanico, who uses Netflix on his iPad Air and on his TV via an Apple TV streaming device. But “Netflix struggles to connect and more often drops to 720 or 480” — affecting picture quality.

Verizon, best known as a wireless carrier, has fiber-optic-based Internet service in some parts of the country. It also has a slower service via phone-based DSL connections in some places.

Comcast recently entered into a corporate branding relationship with Comcast, with agreements to tout each other’s products and services.

Both offer video-on-demand service, including movie and TV-show purchases and rentals, which indirectly compete with the monthly-fee-based Netflix.

And Comcast’s NBC television operations compete directly with Netflix’s original content for TV-viewer eyeballs.

The potential Comcast-NBC market dominance came up as a concern during hearings in 2010 when Comcast was attempting to buy the TV network. And Comcast in 2007 was accused of blocking access to the BitTorrent file-downloading service.

More recently, a court struck down Federal Communications Commission “net neutrality” rules that prohibited Internet providers from favoring one service or app over another. Such rules would have been a clear impediment to throttling of, or other such meddling with, third-party services.

Netflix, for its part, acknowledges problems with its service via certain Internet providers but said the situation does not qualify as a crisis.

“While our ISP Speed Index shows that certain ISPs are delivering slower average connections during prime time, generally our members are able to stream, albeit perhaps at a lower quality and with potentially some start-up delays at the busiest times of day,” spokesman Joris Evers said.

Clearly, though, something is terribly wrong with Netflix for many home viewers.

Netflix’s own Internet-provider speed ranking shows Comcast and Verizon FiOS at or near the bottom of the list. Comcast ranked 14th out of 17 U.S. Internet providers as of January. Verizon was last.

In October, Verizon and Comcast ranked seventh and eighth. In December 2012 they ranked third and fourth, and in November 2012 – the last month on record – they were second and third. The latest ranking and a ranking archive are available at ispspeedindex.netflix.com/usa.

One Comcast subscriber, Dick Lambert of Roseville, has suffered through this issue for so long that he has spent time meticulously documenting it.

When Netflix is on his TV or PC, he said, data rates plunge. The rates are measured in megabits per second. For pristine high-definition gapless streaming, a data rate of about 5 megabits per second or higher is helpful.

Lambert sees excellent performance, often topping 10 megabits per second, when using video services other than Netflix. When he fires up Netflix, however, the data rate will plunge to well below 1 megabit per second.

Lambert said this problem is worst in the evening. Early in the morning, Netflix performance does improve.

Lambert is better equipped than most to monitor such data rates.

He receives video-streaming content via a Sony living-room media player with an unusual feature: It displays a precise data-rate reading each time he pulls up a video-streaming service.

That is why Lambert knew with certainty that his Netflix streaming had become severely impaired last June, improved in July, but deteriorated again just before Christmas, and has stayed that way ever since.

“It would start and then disconnect when I wanted to watch a movie,” he said.

He said Comcast suggested drastic measures, such as replacing all of his broadband and Wi-Fi gear, but nothing made any difference. He was told his Sony media player might be the culprit.

“Everyone was pointing their fingers at everyone else,” he said.

Netflix has offered a potential solution to service slowdowns: an Open Connect service that lets Internet providers connect directly to its streaming service — either over the Internet or by installing Netflix “storage appliances” in or near their networks. Netflix has offered to share Open Connect specs, including hardware and software, with Internet providers as well.

Internet providers that have availed themselves of this tech avenue, according to Netflix, include Frontier, British Telecom, TDC, Clearwire, GVT, Telus, Bell Canada, Virgin, Cablevision, Google Fiber, Telmex and others.

Absent from this list: Comcast and Verizon.