Trying to understand basic packet forwarder on Kerlink Gateway

I doubt it's text, no matter which encoding. In hexadecimal:

$ echo -n "QAMBAQKAWwABp5+scHk=" | base64 --decode | hexdump -C
00000000  40 03 01 01 02 80 5b 00  01 a7 9f ac 70 79        |@.....[.....py|

(Be sure to use echo -n, to not add an additional newline.)