Won't recognize any bulbs

This has been working great for me until the past few weeks now I can't get the smartapp to recognize any bulbs.  It says "The TCP Gateway is not responding..." but I've confirmed it's on/working and IP has not changed.  The only thing I can think of is that I did add a few bulbs recently.  Is there a limit to the number of bulbs that can be on the hub?  Thank you so much for your time/assistance.