All is well. It is installed and running well with no drama on the open sprinkler side of the installation.
I ended up running CAT5 through the crawlspace, however. I could not get the TP-Link to work. It ran it in AP mode for a while and it worked great. In client mode it would work for a few minutes. I would then loose connectivity with both the sprinkler controller and the TP-Link. A few minutes after that all wired and wireless devices would loose connectivity. My raspberry pi weather station (http://188.8.131.52/weather) and media server needed to be unplugged to get them listening again. I tested this several times with and without static IP addresses. By mid afternoon I threw up my hands and ran the CAT5. Any ideas what was happening? My theory is that the TP-Link was offering DHCP renewals even though I had its DHCP turned off. A brief web search found others with similar problems but not as dramatic. They tried different releases of the firmware. I also tried the latest firmware release to no effect.
Both the android and iPhone apps work great.
** edit **
I think I found the problem! It a power supply issue. I can not take credit for finding the solution, however, I found a post from a guy in Britain ( I presume, use of the word whilst) who discover that plugging the TP-Link into a USB 3.0 hub solved his problem. His problem was very similar to mine. The TP-Link in certain operational situations apparently draws at or above 1A. I tried my TP-Link on a 0.85A supply and it would not even boot. If I discover more, I will start a new thread. This strayed from my original topic.
Bill – AB6OR