Model : TL-WR841N

Hardware Version :

Firmware Version : TL-WR841N_V10_150310

ISP :

I have a TP-link router. Model: TL-WR842N , version:10.0
I have had the router for almost a year and there have been no problems until the start of this year when my roommate moved in.

Recently when my roommate connects the internet completely disconnects. There is no internet on Lan cable or on the WIFI, the router is still turned on but the green lights for the wifi and the cable is gone. The only way to get an internet connection again is to power off the router and power it on again.

I do not know if it have something to do with my roommate connecting or not, but i do know that there is no problems when she isn't using the internet. It might just be coincidental that it happens when she starts her computer and use the internet and it might be something with the router. It just seems weird since there never have been a problem before.

so far i have tried:
Resetting to factory default.
I wanted to update the firmwared but there is only the factory default which is: TL-WR841N_V10_150310
Bound every objects MAC-Address til a uniq IP-address.
Set the bandwidth control to 4096 egress and ingress. Even though we have a 120/120 connection.
Called my internet provider to hear if there was something wrong on their end.

Help related to fixing this issue is greatly appreciated.