Three comments:
Your current configuration makes your PI identical to any other pc within your LAN, i.e. it is not in a DMZ. Being in a DMZ means both that ports from the Internet are correctly configured, and that it is isolated from the rest of your LAN so that if an intruder gains access to your Pi server, then he still cannot access the rest of your pcs. This requires a special construct called a VLAN which separates it from the rest of your LAN: the good news is that your LRT214 does this automatically for you if you specify the Pi's IP address within the DMZ mask, as specified at page 16 of the LRT214's User Manual.
The stanza in the
/etc/network/interfaces
should be:auto eth0 iface eth0 inet static address 192.168.73.94 netmask 255.255.255.0 gateway 192.168.73.1 dns-nameservers 192.168.73.1 dns-nameservers 8.8.8.8
Please remember to adapt this to your case.
You are missing the following, all-important
iptables
rule:iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
It instructs the
netfilter
firewall to allow packets (on ports also different than 80 and 22) which pertain to connections which are already under way. The connections under way are both begun by someone connecting to your ports 80 and 22, but also the connections you initiated: if you miss this rule, there will be no follow-up to your own queries, including updates, loading web pages, connecting to local and remote machines, and so on.