print server wireless issue

I have a CISCO router and some times my wireless connection to print server just get lost. I was using D-Link DPR-1260. Then I thought may be the print server is too old.

So I bought a Hawking HMPS2U and found out after I setup for wireless and everything worked fine. But when I power off, then I lost wireless connection.

So I called, the tech guy told me my Cisco router has to be configured to use channel 11, not to use Auto.

So I get to Cisco router and changed the connection to use channel 11, then power off/on both print server and both worked fine.

Oops, I wasted time and money but learned a lesson. My guess is just tuition. Let me see if I can resell this print server or ???