W21 Super Slow Speeds

  • 15 February 2024
  • 2 replies


Hello. I just recently move over to my own hardware from Xfinity. I have a S33 Modem and a W21 Router. I recently upgraded my internet speed as well to 1.2gb. If I run a speed test at the modem I can usually get 1Gb for download. However over WiFi or connecting directly into the w21 with a cable I can only get about 100mb download. I have factory reset the W21 and when I did that I was about to get 900mb on download. 8 hours later it was back at 90mb for download. I’ve been digging through the app trying to find a setting that might be causing it but I can’t find anything. I’ve restarted both router and modem since then and seen no increase of speed. I will say if the router is connected to the 2.5gb port and I connect my computer right into the 1Gb on the s33 I am unable to connect to the modem. However if I restart the modem with my computer connected I will be able to access it when it comes back up. 


Best answer by SURFboard Moderator 27 February 2024, 02:57

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Userlevel 6
Badge +40

Whenever I hear 90mbps, it makes me think its not connecting at gigabit speeds. Here’s what I’d try. 

  1. replace the cable between S33-->W21 with a good quality cat 6. I’ve seen sketchy cat 5e’s drop speeds to 10/100mbps speeds
  2. Try using the S33’s gigabit port. The W21 only has gigabit. Try going gigabit--->gigibit. 
Userlevel 5
Badge +41

S33 is a 3.1 Docsis cable modem , which as got two ethernet ports : One 2.5-gigabit Ethernet port for RJ-45 network cable connection and One one-gigabit Ethernet port for RJ-45 network cable connection.

Depending upon the speed plan, we can connect to either one of the Ethernet port say for instance if the speed plan is within 1 gigabit then the 1 gigabit port will work and if its more than 1 gigabit then the 2.5 gigabit port will work . 

So, both the ports will not work simultaneously .