The ex-Vodafone engineer said he had clocked speeds as low as 300 kilobits per second.
What was happening? Was Vodafone smothering its rival's bandwidth, or was 2degrees being cheap, and buying a minimum amount of bandwidth on Vodafone's network?
Vodafone boss Jason Paris took to Twitter to rule out the former.
And now 2degrees has essentially admitted to the latter - although with the proviso that roaming on Vodafone now accounts for only a tiny portion of its network.
The telco said in a statement to the Herald: "2degrees has invested more than $950m building a national network and we reach 98.5% of the places Kiwis live and work. This includes a small portion (less than 1%) where we pay for access from Vodafone, largely in remote areas.
"We have investment plans to cover this last 1% where customers experience slower speeds than they do on our network.
"In the interim, the reason customers experience slower speeds is because we're putting our funds into expanding the 2degrees network reach and speed, rather than buying faster data speeds in the last remaining areas where we rent."
Onwards to 5G ... sometime
2degrees, Vodafone and Spark are all currently running 4G (fourth-generation) mobile networks.
Last week, Vodafone promised to upgrade a substantial swathe of its mobile to 5G by December, with Nokia Networks as its primary technology partner.
Spark has promised a 5G launch by July 1 next year, and says it will take a "multi-vendor" (read: ditch Huawei) approach if necessary to hit that deadline.
READ MORE:
• 2degrees at 10: the hits, the misses and what's next
• Samsung's new Galaxy Note ditches headphone jack, adds more air gestures
• Spark Sport admits it has lowered its video quality
2degrees, which is an all-Huawei shop, has yet to put a timeline on its 5G upgrade, although departing chief executive Stewart Sherriff said companies had to "stop drinking the 5G Kool Aid". And its new boss, Mark Aue, underlined earlier this week that he sees no compelling near-future benefit for customers.
"4.9G" upgrades to 2degrees existing network will provide enough mobile bandwidth for years to come, Aue told the Herald.
The 2degrees boss is confident that the security concerns that saw Huawei blocked from its first 5G network upgrade application (via Spark) will eventually prove groundless.