I bought an TP-Link Archer C6 Gigabit  MU-MIMO Wireless Router, Dual Band 1200 Mbps Wi-Fi Speed, 5 Gigabit Ports, 4 External Antennas and 1 Internal Antenna WiFi Coverage with Access Point Mode, Qualcomm Chipset from Amazon India on 29 Oct 2020 and started using it a day back with 25 mbps speed from my ISP. However, after 2 months on 10th dec 2020 my plan was expired , so i decided to upgrade my speed from 25 to 50 mbps ,but the time i upgraded the plan  I am facing an issue where in the download speed drops suddenly and recovers after a few mins which occurs frequently . My bandwidth provided by my ISP is 50 Mbps but sometimes the speed drops to 1 Mbps and I checked plugging in an another router so as to rule out the problem with the ISP, but the speed is fine with other router. and also if i connect my laptop via ethernet it is showing 50mbps everytime i check on speedtest . This issue is happening on all the devices connected to the 2.4ghz band on Archer C6. The current firmware version which is installed is 1.3.6 Build 20200902 rel.65591(4555) and there are no updates available via OTA. Also, the ping time becomes very high and also cannot login to the router admin page during this time. However, it becomes normal within a few minutes. Is there any way to fix this because all my work is on wifi and i have to be online for 10-12 hours every day .