Bangladesh had been offline for ten days. Mobile internet was cut on 18 July as the quota-reform protests turned violent, broadband went dark that night, and the country dropped off the map. Limited broadband came back on the evening of 23 July; 4G mobile data returned at 3 pm on Sunday 28 July. By Monday lunchtime, phones across Dhaka showed a 4G icon and delivered almost nothing.
What people measured
Users in Mirpur, Badda, Jatrabari, Shahbagh, Rampura, Panthapath, Karwan Bazar and Dhanmondi told Prothom Alo that speeds had been normal in the morning and collapsed after noon. Tests on fast.com showed 30 kbps to 3 Mbps on networks that ordinarily deliver 30 Mbps and more. The slowdown was still visible at 10:30 pm. Facebook, WhatsApp, TikTok and other social platforms were still blocked, reachable only through VPNs.
What the officials said
Asked why, the state minister for telecoms, Zunaid Ahmed Palak, said the question was for BTRC: “Whether there is a technical reason — BTRC can explain that.” BTRC’s chairman, Md Mohiuddin Ahmed, gave the explanation. Speeds should not be low, he said, and nothing was being reduced from the regulator’s side: “As chairman of BTRC I am saying no speed is being reduced. Rather, we are trying to make it better.” The technical cause, he said, was the caches. “The Google cache was shut; now they are taking bandwidth to update it. We have a great many cache servers — more than 4,000 in Bangladesh, more than half of them Google’s. There has been an effect on international bandwidth.” He added that the blocked social platforms were not saving bandwidth, since people were reaching them by VPN anyway.
What a cache server is, and why the excuse is partly right
When you watch a YouTube video in Dhaka, the bytes usually do not come from California. Google, Facebook, Akamai and others place cache servers inside Bangladeshi ISPs and mobile networks, holding copies of popular content so it is served locally, over cheap domestic links, rather than across the submarine cables that carry the country’s international bandwidth. Normally the caches serve the large majority of traffic. Switch them off for ten days and two things happen when the network returns: every request that would have been local now crosses the international links, and the caches themselves start pulling fresh copies of everything at once to refill. Both put a load on the same expensive pipe. That is a real effect, and it is consistent with speeds being fine in the morning and collapsing as the day’s traffic built.
It is not the whole story. VPN traffic is itself international and cannot be cached; a country that has moved its entire social-media usage onto VPNs is pushing all of it through the international gateway at once. And a regulator that cut the country off is not in a strong position to ask users to take its word that nothing else is being slowed. The caches will refill in days. Trust takes longer.
