Hi all, I'm new here. Hoping someone can help. I've got a basic Arris modem with a TP link router. I've got a 100 MBit ISP plan, but periodically my wifi connection speed slows down to a craw and I have to reset my router by unplugging it. In an effort to fix this, I installed OpenWrt on the router, but it has not helped. I tried to do some troubleshooting next time that it happened, but the OpenWrt GUI showed that the bitrate on the network and Rx/Tx rates for my specific device are still high: imgur.com/BZ93O9T

How do I explain that my internet speed is abysmal? What can I do to troubleshoot further?
imgur.com/6qhfz06

Modem:     ARRIS SURFboard SB6141
Router:     TP-Link TL-WR841N/ND v9