I have a 40Mbps U/D fibre line. Until 1st of March 2023, the router's internal SPEEDTEST used to show the correct speed (~40Mbps U/D) during the test and also had a guaranteed bandwidth of ~40Mbps U/D. 

However, on 3rd March I noticed buffering while watching the OTT platform. I run the router internal SPEEDTEST, and to my surprise, it showed 4~7Mbps U/D speed. To confirm tried bandwidth tests using other speed test websites, those also returned almost the same result 4~7Mbps U/D. 

As per ISP, there is no issue from their side, to prove that ISP has given a standby router to test the Bandwidth and it was giving ~40Mbps U/D. But my AX6000v1 only ~4-7Mbps.

After that did factory reset of my router and tested the speed using internal SPEEDTEST it shows the same ~4-7Mbps, but shows ~40Mbps via other speedtest websites.

Even did FW upgrade but there is no change to the internal SPEEDTEST results.

Internet is working smoothly as expected however anybody have any clue why internal SPEEDTEST is showing wrong information.