Speedtest differences - what gives?

For China Telecom, Ookla, the formerly trustworthy speedtest, is telling me wildly different things to China Telecom's own in-house speedtest. That is, Ookla is telling me what I expect (13M), while China Telecom's netreport is telling me 3-5M, which crappy speed seem corroborated by currently actually crappy net experience. Thing is, I used to have pretty good net experience, and in those days China Telecom's netreport used to tell me 13M too.

Weirdness

Ookla offers two servers in Shanghai, one of which appears to be the China Telecom Branch server. That one gives me the same shitty reading as the China Telecom test results. The other one, China Mobile Group, reports a number matching what my internet speed is actually supposed to be. The Shanghai China Telecom speed test used to be reliable for China Telecom. I guess now it's not.