I work at a hospital to and had to work a lot with our network team to get the 3040s roaming better. Here are the settings that seemed to help our set up.
Roam sensitivity > meduim
Disable Band > 2.4G so it just uses 5G. This helped a lot because most of the hospital’s wireless devices were using 2.4G my network team said that the band is over saturated. This was just done in the last year after upgrading the APs.
Prefer Band > none
Disable N > yes. I got the idea for this setting from another hospital in Washington they said it improved their roaming and it did for our hospital too.
I had to work with my network team on the TCPTosDscp and UDPTosDscp settings. I was told that these setting allow the my network team to prioritize the packets from the thin client. So these settings might be different than what we use but here is what I got on a advanced line. Privilege=High TCPTosDscp=AF31 UDPTosDscp=AF31.