Edgar,
I highly recommend, if you live in an area where there may be overlapping WiFi networks.. use recent OS X's hidden WiFi Diagnostics utility......
Hold down the Option key, click on the WiFi icon in the menu bar and click on Open WiFi Diagnostics... This works for (maybe 10.7... cant remember..) 10.8,10.9 and 10.10.
...and check for any nearby WiFis that may be on the same channel.... and if there are, change your WiFi channel to a different one so your signal remains clear of interference and more importantly uninterrupted... LR seems very susceptible to such brief 'breaks' or interruptions...
Personally because of where I live, there are no competing networks and I have no issues at all using LR with any of my 5 LP rigs here.. switching between them at will....
The only other item of interest that I have found when troubleshooting such issues.. is the use of non Apple Routers..... and a failure of automatic port forwarding for example...but this cause usually prevents connection altogether and not intermittent issues... Haven't come across anyone using an Airport Extreme for example.. from 2009 onwards, who has any issues connecting LR to LPX... but a number of older Netgear, TP-Link and D-Links ones seems to have this issue at times...
Cheers..
Nigel