At times the JioFi 3 router provided Internet speed in my flat in Puttaparthi, Andhra Pradesh, is in the range of 500 to 700 Kbps. Of course, I am talking of situations where I had/have not crossed my FUP limit of 2GB for the day. This can happen during daytime and even during late night time when the speed is typically in the 10 to 15 Mbps range. This happens even when the router is placed at a location where the signal quality is good (green indicator) and where I have got much better speeds of 2 to 5 Mbps during daytime, and 10 to 15 Mbps at late night time.
Now I have noted that when I would be having these low speeds of <= 700 Kbps, and when I checked the status of the router on JioFi administrator page, http://jiofi.local.html/, the operating band would be 5.
Conversely, I have noted that when I get good speeds i.e. > 3 Mbps during daytime, the operating band would be 40.
On browsing the net on the issue I read that JioFi uses operating bands 3, 5 and 40 [See section, “Reliance Jio Band | Reliance Jio Bandwidth” in LTE frequency bands in INDIA, http://www.rfwireless-world.com/Terminology/LTE-frequency-bands-and-4G-LTE-phones-in-INDIA.html]. Band 40 gives the best speed. Bands 3 and 5 give poorer speeds.
But there is no mechanism in JioFi, as far as I know, for the user to safely change the operating band setting to 40. [How to Lock LTE Network to band 3, 5 or 40 [3 Solutions], https://www.newstelecom.info/2016/07/how-to-lock-lte-network-to-band-3-5-or-40-3-solutions/, mentions some pretty involved and perhaps unsafe solutions for handsets (not JioFi routers) to lock onto a particular band.]
My guess is that the JioFi router automatically switches to band 40 if it is available. So no user input is required. At times, perhaps the service provider themselves, may be making band 40 less available or not available and instead making only band 5 (and/or band 3) available. Perhaps one scenario when they do this is when there is high load on the mobile tower at which time, reducing/stopping band 40 availability may allow more people to use the network using band 5 (and/or band 3) but at lower speeds. However, all this is pure speculation on my part and could very well be completely wrong.
From a JioFi router user point of view, I think that when I get poor speeds of <= 700 Kbps, while knowing that the JioFi router is not on Operating band 40 gives me some idea of the problem, I do not have any solution to increase the JioFi router speed. I typically have to either switch to using the Huawei 4G USB dongle and its SIM OR wait for the JioFi router to automatically move to Operating band 40. Typically I have seen that the JioFi router is stuck at Band 5 and lower speed (<= 700 Kbps) only for half an hour to an hour. After that period the router switches to using Band 40 and typically gives 2 Mbps or higher speed.
Today (14th Oct. 2017) around 2.15 PM in the afternoon, I had this low speed of 500 to 700 Kbps problem (fast.com used to measure speed). This continued for about 20 to 30 minutes. Switching off and then switching on the router had no impact.
Then around 2.50 PM the operating band changed to 40 (on its own) without any effort on my part, and the speed jumped to 4.9 Mbps (fast.com). [I had just plugged in the Huawei 4G USB dongle with my other Jio SIM (whose initial validity of 84 days will expire in a few days time) but had not connected to the Internet with it. I don’t think just plugging the Huawei 4G USB dongle in would have had any impact on the JioFi 3 router changing the operating band to 40. Once I saw that the operating band has changed to 40 and that the speed had got into healthy 2+ Mbps range, I unplugged the Huawei dongle (without having connected to the Internet with it).]
I have observed during such times of 500 to 700 Kbps speed of JioFi 3 router, if I use the Huawei 4G dongle (with another Jio SIM) instead, I get 2 Mbps+ speeds usually. But at times, even with the Huawei dongle, the speed goes below 1 Mbps touching 800 to 900 Kbps. In general though, the Huawei dongle gives a better speed solution when the JioFi 3 router is stuck at 500 to 700 Kbps speeds (and Operating band 5 (or 3)).
The Mobile Partner program that comes with the Huawei dongle did not seem to have any property field showing operating band. So I don’t know what operating band it uses.
*) At 3.03 PM got 1.9 Mbps speed (fast.com) with JioFi 3 router (with operating band 40). 2 to 3 Mbps speed during daytime, in my Puttaparthi flat, is not unusual with JioFi 3 router (or with Huawei dongle). And this speed is typically good enough for quick viewing of images while scrolling down Facebook Timeline and seeing youtube videos without pause for buffering.
*) At 3.07 PM got 4.9 Mbps speed (fast.com) with JioFi 3 router.
*) At 4.35 PM got 8.5 Mbps speed (fast.com) with JioFi 3 router. Operating band is 40 and Bandwidth is 20 MHz.
*) At 5.12 PM got 2.2 Mbps speed (fast.com) with JioFi 3 router. Operating band is 40 and Bandwidth is 20 MHz.