What "hnyman exactly"?
The TFTP recovery process has been described in detail in Netgear R7800 exploration (IPQ8065, QCA9984) - #5 by hnyman and so far it has worked 100% ok for me for maybe a dozen times during the past two years.
EDIT:
I got recently trouble with TFTP2 that I used earlier, so I switched to use tftpd64 which has worked ok with R7800 and the current master and 18.06.