ASUS RT-AC68U speed will throttle down to 100/100mbps

[Kingfapa]

Hello,

Since November 2018 have I been having issues with my ethernet speed.

I pay for 250/250 which I got when I setup the LAN for the first time but after having that speed for maybe about a month it throttled down to 100/100.

I tried swapping the router/cables, changing firmware both Asus stock firmware, Asuswrt-merlin and DD-WRT (which is my current firmware), changing duplex on the router but nothing worked.

After a couple weeks I figured out that if I repeat the following things my 250 speed will return:
- turning off the router and power cycling it
- plugging in my computer directly to the modem, changing duplex on my network card to try to force 1 Gpbs duplex

This can take from 2-15 min depending on how many times I have to repeat it.

But the speed will only stay at 250/250 for a couple weeks before throttling again down to 100/100

I have been in touch with my ISP but they say that everything looks fine at their side and the only thing they have done is to change the switch in my apartment complex which they did around january 2019.

Does anyone have an idea how I can keep my speed to stay at 250/250?

 

[drabisan]

68U does not have this problem.
First and foremost you should replace the eth cable between router and modem.
Second, remove what services are not really needed, like Trendmicro c..p.

 

[Kingfapa]

I have replaced the cable multiple times between my router and modem.

I am also using DD-WRT where I have disabled every service except DNSMasq and Syslogd.

 

[cplay]

Have you tried a different router?

That way you can rule that out after like you say you've ruled out cables?