NextCloud snap and CloudFlare reverse proxy

Edit NextCloud config file:

sudo nano /var/snap/nextcloud/current/nextcloud/config/config.php

Add the trusted proxies configuration. The first one is your local reverse proxy address (for example Nginx Proxy Manager), the rest are CloudFlare’s IP ranges:

    'trusted_proxies' => 
  array (
    0 => '10.220.2.1',
    1 => '173.245.48.0/20',
    2 => '103.21.244.0/22',
    3 => '103.22.200.0/22',
    4 => '103.31.4.0/22',
    5 => '141.101.64.0/18',
    6 => '108.162.192.0/18',
    7 => '190.93.240.0/20',
    8 => '188.114.96.0/20',
    9 => '197.234.240.0/22',
    10 => '198.41.128.0/17',
    11 => '162.158.0.0/15',
    12 => '104.16.0.0/13',
    13 => '104.24.0.0/14',
    14 => '172.64.0.0/13',
    15 => '131.0.72.0/22',
    16 => '2400:cb00::/32',
    17 => '2606:4700::/32',
    18 => '2803:f800::/32',
    19 => '2405:b500::/32',
    20 => '2405:8100::/32',
    21 => '2a06:98c0::/29',
    22 => '2c0f:f248::/32',
  ),

You can find an updated list of CloudFlare’s IP ranges here:

https://www.cloudflare.com/ips/