[newbie] intercept iOS on RPi (ubuntu)

Newbie here.
I like to intercept app traffic from my iPhone. I installed mitmproxy on a Raspberry Pi. I have applied the following on it:
sysctl -w net.ipv4.ip_forward=1
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 8080

I start mitmproxy with
mitmproxy -T --host

I deployed the cert on iOS.

However, when I set the “HTTP proxy” and “router” (on ios) to my raspberri pi and port to 8080, safari won’t browse.

Should I undo the iptables and sysctl settings? I don’t think I have an firewall on the Ubuntu raspberry pi that prohibits usage of the ports? Is there a way to check this (it should be the “simple firewall” if any)

I fixed it. Running mitmproxy without the above options helps.