Our current ISP provider is 2 degrees and we use a fritz box router that shows the dsl connection speed when accessed into the routers settings (As shown in the picture).



I installed a cat5e cable along with a master splitter that connects directly to the router instead of using the phone jack to connect to the router as we have been getting varying internet speed depending on the phone jack. Before cat5e/splitter was installed, we were gettimg around 8.5mbp/s ~ 8.8mbp/s in download speed.
When we first installed the cat5e cable with the splitter the speed increased to 9.5 the to 10, 11 and eventually reaching a peak speed of 12.2 mbp/s within a week.
Could tell the speed was increased even by testing on sppedtest.net.
The following week, i observed the reverse as the speed decreased gradually back to 9.2 mbp/s. The router would automatically disconnect around 3 or 4am and re adjust the speed. It never went back upto 12.2mbp/s

Anyone know why this process happens?
(Ipv6 is connected when connected at the speed of 9.0mbps but only ipv4 was connected at 12.2mbps)