Vodafone router does not allow to turn off firewall permanently. It will insist on switching it on after 24 hours.
Version of this router in question:
Firmware version: 01.02.037.03.12.EURO.SIP Productname: Vodafone Docsis 3.1
This “Made in China” router using Linux 3.12.59 from 2010, is teaching the “expert user”. You have to get “expert user” if you want to switch off firewall. As of the time of writing, stable Linux kernel version is 5.5.6, longterm 5.4.22, earliest is 3.16.82. It is also using old versions of
Apparently the creators of this router never thought of any user employing Linux and
iptables, or something similar.
Luckily, the router allows to forward a range of ports, thereby effectively bypassing the firewall.
See Home Router Security Report 2020 for an assessment of home-routers.