If you need a partial quick fix fast, go straight to the last paragraph. Otherwise, here are the details:
I present almost every day using Keynote on my iPad2 with Keynote Remote on my iPhone5 (to run the presentation). I link the two devices using Personal Hotspot (my phone’s WiFi network) so as not to be at the mercy of the WiFi network in whatever random location I’m visiting. I use this Hotspot mode because it’s more reliable than Bluetooth (but read on). Most hotel WiFi networks won’t work for this application.
When I upgraded both devices to iOS7 (on day 1), this configuration no longer worked. Keynote Remote locks up (freezes) when using Personal Hotspot.
Here are a bunch of things I tried that had NO EFFECT on the problem: Kill and restart Keynote and/or Keynote Remote Apps; Power-cycle (reboot) iPad and/or iPhone; Hard-power-cycle (by holding down the power and home buttons simultaneously until the Apple logo appears) iPad and/or iPhone; Reinstall Keynote Remote; delete the original remote (in Keynote, click the wrench and select “Advanced” and then “Remote”) and/or re-add the remote; and so on.
Or if your Hotspot is active and Keynote Remote is already running on your iPhone (on-screen, not in the background), you’ll get the message “Unable to join the network ‘Your iPhone’” when you attempt to connect your iPad to your iPhone’s WiFi).
If Keynote Remote is in the background and then you link your iPad to your iPhone WiFi network, you’ll find that Keynote Remote is frozen. Even if the App is restarted it will be frozen. If you disable the Hotspot, Keynote Remote will unfreeze (although that’s not very useful).
Bottom line: As of today, I’ve found no way to get the iPhone Personal Hotspot mode to work with Keynote Remote (let me know if you discover a fix). However, I have found one very specific workaround. Here it is.
On your iPad, turn on Bluetooth (WiFi setting doesn’t matter) and open Keynote. On your iPhone, TURN OFF Personal Hotspot, turn on Bluetooth (WiFi setting doesn’t matter), and start Keynote Remote. Wait about 5 seconds for the devices to link by Bluetooth and you’ll be able to “Play Slideshow”. Note: If the devices have not previously been linked (or won’t link), you’ll have to TURN ON Personal Hotspot, link by Bluetooth, TURN OFF Personal Hotspot, and then proceed as above. I know… it’s crazy but it works!