Questions regarding TP_Link MR6400 V5

Hi,
i'm trying to install Openwrt on this TP-Link, but i'm not able to get a working TFTP connection.
So there are 2 (maybe dumb) questions:
the doku says:
192.168.0.225 is the server (subnet mask 255.255.255.0)
192.168.0.2 is the client
...but is the router the server or the client?
...and are this IP-addresses really correct?...cause when booting in "nomal" mode, the router has the IP 192.168.1.1
hoping for clarification and best regards

It says:

serve tftp-recovery image as tp_recovery.bin on 192.168.0.225/24

The router is the client.

The documentation says:

power on the device while holding the reset button

This seems to activate "TFTP mode", but you'll have to wait for another user who owns the device if you want to double-check the documentation is accurate.

short update: addresses are correct - virus scanner blocked the traffic.