I'm getting the same error on my RTCM that uses a GPS-18. I have 1 T/R site and 1 Rx only site, the T/R site is the only one complaining of "Warning: GPS Data time period elapsed" This just started a couple days ago, 15th or 16th I believe.
Also I'm getting a "Inbound (Eth Rx) packet out of bounds by: -1" error
In the past I had guessed the out of bounds by -1 error was caused by poor GPS signal, as I had seen different system that uses a Trimble Thunderbolt do the same thing. The GPS antenna on that system was getting RF swamped by the VHF transmit antenna, in the Trimble Software you could see all of the Satellites drop off when ever we keyed the transmitter. I would see the transmitter come up for a second then drop, then come up a while later, then drop.
On this system when I switched my RTCM to GPS Data Protocol to TSIP, then back to NMEA it reported 10 Satellites to the RTCM. I've also had problems with the 10 Mbps connection and some managed switches. Doesn't matter if I choose 10 Half or 10 Full, I get collisions and errors reported by the switch on that port. I have to believe the switch is telling me the truth, so therefor there is something wrong with the Ethernet protocol in the RTCM's.
All this work on my GPS-18 RTCM was done remotely on the 17th as there is too much snow to access the RTCM. At the end of the day I gave up and crippled the server link causing to T/R site to go into local repeat.
73
Jesse VE7LYD