The high school was built as a bomb shelter for world wars, and therefore is reinforced concrete with rebar metal rods inside.  They designed the access points to be out in the halls to service about 4-8 rooms apiece.  Signal quality getting into classrooms was definitely by far not stellar for 20-160 devices each access point serviced.  To top it off, for one room, they put an access point in our attic space to service a large room beneath it, through the reinforced floor… and didn't tell anybody it was up there.   

When I first started working with one of my customers, they had 5 different access points and every one of them had a different SSID and security key. Employees with laptops had to connect to a different AC every time they went into another part of the building.  

When updating the wireless at the fire station, I found 4 different wireless routers, all set to offer DHCP, all running in the same building.  

I once did an entire network from scratch for a new chiropractor and her new office. Domain controller, server, switch, cable runs, computer setups, etc… Everything was working flawlessly. Then she decided not to consult me and installed $10,000 office software on an all in one desktop….. I came back a couple years after the fact and they switched ISPs and were daisy chaining a new router with the old setup and it was a hot mess. And she thought she couldn't use a wireless keyboard/mouse because she thought it violated HIPAA policies. Well, given that a lot of wireless keyboards and mice signals are not being encrypted, I would say that would probably violate HIPAA rules since anything typed can be sniffed from a distance away.  

When I was interviewing for my last job they told me that they’re having horrible wireless issues to the point that no one wants to use it so they ran cable recklessly through the shop and warehouse to get to areas that they needed connections. When I got hired they said that figuring out the wireless issue was my top priority.  For the first few days I monitored the wireless connection nonstop and had no issues.  Soon after that I was watching the wireless and it dropped for several minutes and then was back up.  This cycle of stability then dropping continued for weeks before I finally figured out what was happening.  One of the guys in the shop only periodically worked in the area of the shop where the wireless AP was plugged in and he would unplug it to run his tools then plug it back in when he was done.  He had no idea that he was unplugging the wireless.  After figuring this out the wireless connection was perfectly fine.  

Wi-Fi nightmare is when you have buildings across the street and they need internet. We don't want to pay for internet at each location, and we don't have the credentials to string wire on telcom polls. So we did the next best thing: Wi-Fi bridge for buildings across the street. For the most part it has been stable but our new sales department was down three days while scrambling finding a replacement device that had to be ordeedr because of the lack of planning and then configuring it. I was able to configure and get it put back on the poll. Then 30 minutes later it crashed again, power cycling didn't help and we had to start over from scratch in configuring.  

When I first started at the company I found out that the Wi-Fi password was the sysadmin password and that it was given out to anyone who asked for access to the Wi-Fi (including guests).    

From my previous job as an ISP tech support agent: Got a call from an upset customer with a tech onsite. "We've had a tech out here to fix this multiple times! Every time they are here, the internet works fine but as soon as they leave, everything stops working!" The guy hands the phone to the tech and leaves the room. Upon leaving the room, he turns off the room light by habit. The tech, still examining the equipment, watches as all of the equipment loses power as soon as the lights go out. "I think I just figured it out,” he says. ROFL, the power strip with everything plugged into it was plugged into a wall jack controlled by a light switch! Every time the owner left the room, he was powering down all his equipment when he turned out the lights including his wireless router!  

At my past job, the tech team decided to place an old refurbished Wi-Fi router on the other side of the 300yd long warehouse, opposite of the side where the management offices were.  

One time we spent a week troubleshooting an issue with a wireless bridge where it would only transmit in half-duplex and only one connection at a time. We found out that by simply selecting a check box for Transparent Bridging, it fixed everything.