Lots of picky people!
Of course wired is the best option. But the main use of a laptop is it's portable...And the main use of wifi is so you can stay portable.
Yes, you will get more reliability and speed out of wired, but Wifi is good enough. If your wifi messes up, and you just NEED to get the file sent over.. it's a 2 minute walk to a port where you can plug in and send it that way. So, I don't see the big problem... It's giving you the convenience you need, and if it goes down at the worst moment, you have a backup.
Now onto the question at hand... 1 year for a router is pretty bad. How many people are on your router? Our office/Warehouse has about 30 people, the Wifi is great... But as soon as it hits 12, and theres 20+ phones connecting to wifi, it crashes or goes as slow as possible.
I brought a home router - Plugged it in and set it up as an Repeater. Now while all their phones lose connection... I ALWAYS have a strong good signal for my laptop, which I pretty much do the same thing you do with.
Maybe look at segregating the internet - Have a router setup as a repeater in the warehouse, and one in the office - You're not limited to 1 router. And depending on how many people you have... A consumer grade router might not work. Consumer grade routers are meant for a couple people only. Every person you add halves the bandwidth (Not exactly halves.. but for the sake of this argument, we'll say it halves). Business grade routers generally have AP's with their own hardware that splits the workload.
I suggest buying the router I linked (That you wanted anyays) Set it up in the warehouse, even if it means running a new wire to the warehouse. You can give it it's own Network ID and pass, and just not tell anyone the information. Then you have your own dedicated router that wont have slowdowns from other people, wont have ramleaks (Which most routers seem to) and crash every other week, etc.
That's likely your best option if you want the most reliability out of wifi.