I have the "Ultra Fast" 900mbps Xfinitity plan with a CBR40 modem/router and RBS20 satelite. I've never seen speeds quite near 900, but in the past it's been quite good (at least 300-400mbps over Wifi). Lately I'm only seeing speeds of 30-40mbps over wifi when using either Googles speed test, or speedtest.net. I do not have a way to check my wired speed other than using the app because I don't have a computer with an ethernet port. I recently did a factory reset on the router, and updated the firmware to V2.5.0.24_1.0.8 with no changes noted. I've had the ISP send a tech out and they routed a new cable to my house which also had no affect. ISP says my connection is good up to the modem. I have also noticed since doing a factory reset that my devices are having trouble connecting to my wifi, they are constantly dropping off. This was not an issue before. I have no splitters between the main cable and the modem. Wifi channels are set to auto.Armor, Circle, Daisy Chain, Fast Roaming, IPv6 all disabled. Please help. I'm ready to just bite the bullet and go buy a new modem or rent one.

What wireless devices are you using when speed testing? What channels are you using? Be sure Beamforming and MIMO(MIMO may or may not be needed) and WMM are enabled. Under Advanced Tab/Advanced Settings/Wireless Settings. You can disable MIMO as a test to see if this changes anything. Set 20/40Mhz Coexistence to 40Mhz only.

The speeds you are seeing are generally normal for something on 5Ghz AC. Most devices max out at 300-500 depending upon there design. If your in a noise wifi environment, this can cause problems as well. Try turning down the power output of the RBRs wifi radios from 100% to 50% and see if this changes anything. Under Advanced Tab/Advanced Settings/Wireless Settings Rac1ngSnak3 wrote: I'm in a similar situation. Xfinity 600 mbps plan connected to Orbi CBR40 and 2 satellites (RBW30 and RBS50Y). On Ethernet (AppleTV, Speedtest app) directly connected to CBR40 I actually get better than advertised speeds at 715 mbps (don't tell Xfinity). But when I use a WiFi device I'm maxed out at about 300 mbps (280-315). Beamforming is enabled and MIMO is enabled, and 20/40 MHz coexistence is disabled. WiFi devices are on 5GHz and "connected" to the CBR40. 8 devices are on the WiFi network. WiFi space is pretty dense as we're in an apartment complex but S/N seems good inside our apartment. I'd expect WiFi speeds to be a little higher maybe in the 500 mbps range. What's the fastest speeds people have seen with their CBR40 on WiFi?

Check the device you're testing on to see if its on 2.4ghz or 5ghz. 2.4ghz is a slow network and those speeds are about right for 2.4ghz. 5ghz is much faster.

If you have a PC or laptop that does not have a ethernet port, you can get a USB to ethernet port adapter to help with testing wired speeds. The CBR40 should see near 800-900Mbps depending upon if ISP supports on DOCSIS 3.0 it and all 32 channels are locked in. Most ISP now days require a DOCSIS 3.1 modem for 1Gb services.

All the devices I've tried doing a speed test on are on the 5ghz network. What do you mean by "all 32 channels are locked in" ?

Extremely slow CBR40 Speeds, need help

12 Replies

FURRYe38
Guru
Nov 17, 2021
If you have a PC or laptop that does not have a ethernet port, you can get a USB to ethernet port adapter to help with testing wired speeds.

The CBR40 should see near 800-900Mbps depending upon if ISP supports on DOCSIS 3.0 it and all 32 channels are locked in. Most ISP now days require a DOCSIS 3.1 modem for 1Gb services.
- MP1987
  Aspirant
  Nov 17, 2021
  All the devices I've tried doing a speed test on are on the 5ghz network.
  
  What do you mean by "all 32 channels are locked in" ?
  - FURRYe38
    Guru
    Nov 18, 2021
    The channels seen on the Cable Connection Status page.
    
    Will look similar to whats seen here:
    
    https://community.netgear.com/t5/Orbi-with-Built-in-Cable-Modem/Upstream-light-blinking-with-no-internet-issues/m-p/2159540/highlight/true#M2629
    
    What wifi devices do you have connected to the CBR?
plemans
Guru
Nov 17, 2021
Check the device you're testing on to see if its on 2.4ghz or 5ghz.

2.4ghz is a slow network and those speeds are about right for 2.4ghz. 5ghz is much faster.

Forum Discussion

Extremely slow CBR40 Speeds, need help