I have both PC Connect and a bridge reporting to MBW, and have never received a "server error" from the iPhone app or on the MBW web site. The only repeatable issue that I've ever had is that for some reason PC Connect updates seem to stop for over 20 minutes whenever there's a significant weather event here in the northeast. The bridge keeps updating though, go figure. Are you using all of your iOS devices over a home wifi? If so, can you try using the iPhone over the cellular link and see if it makes a difference?
If your home ISP is playing games with DNS redirection for unknown web sites, a slow DNS response for MBW could redirect your app traffic to a web server farm that your ISP runs with their own search engine. It works for simple cases and web browser traffic, but breaks every other TCP/IP application and could legally be considered connection hijacking if someone wanted to pursue it in court. Time Warner has been using this for several months locally, and annoyed me enough where I changed over to using Google's free public DNS server at IP address 8.8.8.8 in my router since it responds properly when a name doesn't resolve in a timely fashion. Anyway, if you don't have a problem over cellular but do over home wifi, this is one thing to try.
Regarding the humidity sensor problem, there is a known problem with 5-in-1 sensors produced before 6/2012 showing erratic humidity readings. Acu-Rite has extended the warranty for them, and will make it right if you contact customer service. There are several posts here and in their own online support forums about the "98% humidity" problem, and what the extended warranty procedure is. My 5-in-1 (purchased 12/2011) has this problem, but I haven't had the inclination to warranty it since I have a second 5-in-1 sensor. You may also want to give their tech support a crack at your first question, because they might have seen it with other customers.....
