I just followed up following steps to harden network security

The /etc/sysctl.conf file contain all the sysctl settings. Prevent source routing of incoming packets and log malformed IP's enter the following in a terminal window:

sudo vi /etc/sysctl.conf

Edit the `/etc/sysctl.conf` file and un-comment or add the following lines :

# IP Spoofing protection
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1

# Ignore ICMP broadcast requests
net.ipv4.icmp_echo_ignore_broadcasts = 1

# Disable source packet routing
net.ipv4.conf.all.accept_source_route = 0
net.ipv6.conf.all.accept_source_route = 0 
net.ipv4.conf.default.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0

# Ignore send redirects
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0

# Block SYN attacks
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 2048
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 5

# Log Martians
net.ipv4.conf.all.log_martians = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1

# Ignore ICMP redirects
net.ipv4.conf.all.accept_redirects = 0
net.ipv6.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0 
net.ipv6.conf.default.accept_redirects = 0

# Ignore Directed pings
net.ipv4.icmp_echo_ignore_all = 1

To reload sysctl with the latest changes, enter:

sudo sysctl -p

But, after applying the changes I found "Wi-fi" downloading speed and terminal downloading speed extremely slow (less than 1KB/s) however surfing speed through browser was good. But, using direct ethernet cable was giving a good speed.

Then, I reverted back the above changes and things fall back in line once again....

Could you please let me know what possibly in above script is affecting such behaviour [and why] ? How could I still maintain hardening of network security without disturbing Wi-fi downloading speed ?