Apple today quickly exhausted its pre-order supply of the larger iPhone 6 Plus as the company bungled an online effort for the second time this week.

As of 9 a.m. ET, the iPhone 6 Plus, the model with a 5.5-in. display, was listed on Apple's U.S. online store as shipping three to four weeks after ordering. The iPhone 6, which boasts a 4.7-in. screen and is the more direct successor to the iPhone 5S, remained in stock, at least on the Apple store, with deliveries promised by Sept. 19, a week from today, when the new smartphones go on sale in the U.S. and several other countries.

Short supplies are nothing new for Apple and its iPhone at on-sale launch, and even more so when it offers pre-orders. In 2012, for example, the then-new iPhone 5 sold out in about an hour. Last year was abnormal, in that Apple did not offer the more-appealing iPhone 5S for pre-order, only the less-expensive iPhone 5C, which sold poorly at the beginning.

Nor have those online pre-orders always been problem free. But the technical issues went beyond glitches this time: Many reported on Twitter that the Apple Store was unavailable hours after the 3 a.m. ET kick-off (midnight PT).

It was the second black eye for Apple in the span of four days.

On Tuesday, when Apple hosted a news conference to unveil the iPhone 6 and 6 Plus -- as well as its new electronic payment system, Apple Pay, and its first wearable, the Apple Watch -- the live webcast was a mess. For between a third and a half of the one-hour-and-45 min. broadcast, people faced constant interruptions, black screens, failed audio, pre-show color bars, repeats of parts already seen, several "Access Denied" error messages, and a Chinese translator talking over CEO Tim Cook and other Apple executives.

Customers -- potential customers might be more accurate -- took to Twitter to vent their frustrations early this morning. "I feel like it's Tuesday and I'm watching the Apple Event live stream drop out," said Dan Frakes, formerly with Macworld, in a tweet. "There's even Chinese writing on my Apple Store page."

Some, including at least one Computerworld staffer, managed to score an iPhone 6 Plus this morning, but only after using the Apple Store app on his iPhone to place the pre-order.

The quick disappearance of the iPhone 6 Plus from immediate availability was not unexpected: Talk of short supplies had circulated in the days and weeks before Tuesday's introduction, enough so that some speculated Apple would not even unveil the larger iPhone, and would instead wait until later in the year, perhaps even early next, to start selling the 5.5-in. so-called "phablet."

"In our view, the weakness in our Apple Barometer, Hon Hai Precision, and other Apple suppliers during the month of July was an indication that the supply chain began ramping production for this iPhone launch later than in the past," said Brian White, a financial analyst with Cantor Fitzgerald, in a Friday note to client. "[This] will result in supply constraints for the iPhone 6 and severe supply constraints for the iPhone 6 Plus."

White also pointed out the short supplies at U.S. carriers. As of 11 a.m. ET (8 a.m. PT), AT&T showed a 7-14 business day delay in shipping new orders, while the carrier stretched the iPhone 6 Plus ship date to 32-45 business days, up to nine weeks, or as late as mid-November.

Analysts have debated which of the two models will ultimately sell more units. Most have predicted that the less-expensive iPhone 6 will dominate. But a few have started to hedge their bets, believing that there is even more pent-up demand -- especially at the beginning of the sales cycle -- for the iPhone 6 Plus and its larger screen on the part of current iPhone owners and those who went Android because of the bigger displays offered by Samsung.

Apple did not include the People's Republic of China (PRC) in the first wave of iPhone 6 markets. While state-run media speculated that the omission of the PRC was due to everything from sluggish regulatory approval to a desire by Apple to punish domestic carriers for leaking details, Apple may have simply decided to postpone the introduction because of inadequate supplies.

Larger-screen smartphones are particularly popular in Asia in general, and in the PRC in particular, and Apple may not have wanted to start selling the iPhone 6 Plus in the latter until it had a larger inventory.

That was White's take. "I think it was supply issues," he said in an interview. "The technical reason is that they haven't gotten approval [from the Ministry for Industry and Information Technology (MIIT)], but if Apple had wanted to sell in China, it would have gotten it done. The iPhone 6 Plus could be off the charts in China, but why put another wrench in sales if they didn't have to?"

White said he expects Apple to begin selling the iPhone 6 and 6 Plus in the PRC in a month or so.

Apple will begin sales of the new iPhones in its retail stores on Friday, Sept. 19, starting at 8 a.m. local time.