I would STRONGLY recommend that you update your client drivers, as well as update Windows to latest build level as there are fixes for these timeouts. ANY wireless issue should trigger you to check that the latest drivers are installed!!!   In addition, there are also issue with latest Windows builds and 11r. If you see an "invalid MIC" issue then disable 11r for that SSID. My understanding (I may be wrong) is Microsoft are working on a fix but it'll be a while. ... View more

3 ceiling mounted APs should get you the coverage for 120m long isles., but you will not get any overlap at the end of the isles, so the client may not be able to select the next AP in time to roam cleanly.   If you can get higher gain on the client side all the better.    At the end of the day, you may have to go onsite and try a few different scenarios to check coverage, and it may never be perfect.   @PhilipDAth Not a good idea with the AP. AP to AP mesh is generally not designed for roaming. However, a wireless bridge, which is in effect a client with an ethernet output might help. ... View more

There's certainly pro's and con's of both approaches. Generally wall mounted will reduce the number of APs required but if the walls are too close to  the end of the isles you won't get a lot of overlap.    Ceiling mounted uses more APs, and they generally are installed with clear line of site between them with little spacing, meaning you get a lot of CCI and ACI.   With forklifts moving up to 15kmh, overlap is crucial for roaming. This can be problematic to achieve with floor to ceiling racking.   If you can wall mount, and alternate the APs between the opposite ends of the isles you may get a good result. ... View more