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Welcome!- Has a Factory Reset been performed?
- Was a Factory Reset performed before and after any firmware updates then set up from scratch?
FW Update Process- Was the router working before any firmware updates?
Is the managing PC the only device connected to the router when you set up the router and let it perform it's speed test? Ensure no other devices are connected and streaming while you set up the router...
What happens if you manual input 100/20 in to the SB/ABE window?
Ensure that the ISP modem is bridged fully.
Is the ISP modem using Dynamic or Static IP addressing?
You can pick what ever channel you want on the radios...
Web Browser ConfigurationsWhat browser are you using?
Try Opera or FF? If IE 8, 9, 10 or 11, set compatibility mode and test again.
Disable any security browser Add-ons like No Script and Ad-Block or configure them to allow All Pages when connected to the router.
Clear all browser caches.
Be sure to log into the Admin account on the router.
Try turning off these features in Chrome: Top right corner, little bars for options > Settings > Settings (on left) > Show advanced settings.
Uncheck these:Use a web service to help resolve navigation errors
Use a prediction service to help complete searches and URLs typed in the address bar
Predict network actions to improve page load performance
Enable phishing and malware protection
I have the DGL-5500 fully updated with this issue (Pipe in use, aborting test)
My other issue is still ongoing after talking to the D-Link Support that had me switch from Channel 11 to channel 6 to fix an issue with Network Active devices not showing up.
Sorry to say but still an issue. 
I called D-link support 3/3/14 and was on hold for 45 min only to hear phone ring and click. Hung up.
Not how you treat a customer.
1) Current Firmware Version : 1.11 Date : Purchased 11/13/2013 and updated
2) Florida, USA.
3) Wired and wireless
4) Factory reset yes and backed up.
5) Factory reset yes and backed up.
6) Cable Bright-house
7) Ubee DDW3611 Lighting 90mbs down, 15 up. setup as Modem is Bridge
9) Cable 1500
10) Always on is on.
I have been a D-Link customer for well over 20 years and I have setup many home & office networks.
From what I am seeing DGL-5500 needs a firmware update to let the customer pick what ever channel they want and to also fix network active devices issue.