I’m dealing with 8 GXP2130’s all running 18.104.22.168 for the firmware. Obviously, that’s quite old. I’ve been trying to get them to upgrade with no luck. No matter how I try, whether it be via local TFTP, or using the grandstream http server. They just will not upgrade. The first step for the newest firmware is to go to 22.214.171.124, which the phones will not upgrade to.
For 4.23 i found best upgrade to 5.xx first. (126.96.36.199 for example)