When using a rover that utilizes RTK fix, it is important to be aware there may be circumstances that cause your device to lose its corrections and fall back to 3D/DGNSS. This could be due to an interrupted internet or L-Band connection.
If you are using the F9P, F9R, or F9K and you want to delay the fallback time to DGNSS, you can modify the CFG-NAVSPG-CONSTR_DGNSSTO configuration value. This value can be adjusted from 1-255 seconds, with a default value of 60 seconds. It is important to keep in mind that as the corrections get older, the accuracy of the solution will slowly degrade (few centimeters per minute) since the corrections are not updated anymore. This is because the longer the time without correction updates the higher the mismatch between corrections and actual error states leding to a higher position error.
When the corrections are received again and the receiver still holds RTK fix it will recover its accuracy relatively quickly within a few seconds.
If the outage was too long and the receiver was in 3D/DGNSS mode the receiver position immediately jumps back up to meters when getting new corrections again, depending on the actual offset between both solutions.