At startup the B4R log shows random characters in the log. This isn't normally a problem but I'm trying to test the deep sleep function of the 8266. This mans that every time it restarts and something is sent to the log these characters are displayed.
If this is happening when going in to or (more likely) out of deep sleep mode, then one possibility is that the UART is being put to sleep in the middle of transmitting a byte. When it later wakes up, it merrily sends the remaining part of byte, which will be misinterpreted by the receiving UART of the serial-to-USB bridge.
You could try forcing the junk to occur by sending a long log just before going into sleep mode.
Or you could send a short log last thing before sleeping and first thing after waking, with a (say) 1-10 ms delay after the going-to-sleep log, eg:
Log("Sleeping")
Sleep(10) 'allow enough time for this message to get through the UART and USB bridge
GoToDeepSleepMode
Sleep(2) 'perhaps also try giving the log UART a moment to spin up
Log("Waking")