Remotely connect to computer when connection partly fails

Question

I have a Debian computer acting as a server at home. It has a dovecot+postfix mail server, an SSH server, an apache server, and everything you would expect from a do-everything server.

At home, it is connected via ethernet thanks to PLC. The PLC I bought was a cheap one, and occasionally, it stops working.

I'm very far from home (I'm in Africa right now, and my computer is in Europe), and the PLC just stopped working. My computer is behind a NAT, but I took care forwarding all ports to the ethernet connection that is now dead, and I'm left with the WiFi connection I didn't specifically forward any port to.

I'm looking for a way to connect to my computer, I forgot to forward a few ports through the WiFi connection before leaving, and strangely enough, the Apache server seems to answer all my requests: I can access to my WebSite. Right now, I'm mostly concerned with emails, because they were all coming to the ethernet connection, and now I'm afraid they'll be lost. I have mosh installed if it can help.

Here is a little sum up/TL;DR:

• Computer: Debian testing acting as a server
• Connection: Ethernet + WiFi
• NAT settings: Forwards a lot of TCP ports to Ethernet, none to WiFi
• Issue: Ethernet stopped working, so I'm only left with WiFi
• Additional informations: The Apache server seems to answer requests, also there is no specific port forwarding. I have a digital ocean server, and I can modify my dns records to forward anything to this specific server.
• Question: How could I establish a connection to my computer? Or at least, how would I go saving all emails to another server

nmap tcp scan report:

Not shown: 984 filtered ports
PORT     STATE  SERVICE
21/tcp   open   ftp
80/tcp   open   http
554/tcp  open   rtsp
1720/tcp open   H.323/Q.931
6000/tcp closed X11
6001/tcp closed X11:1
6002/tcp closed X11:2
6003/tcp closed X11:3
6004/tcp closed X11:4
6005/tcp closed X11:5
6006/tcp closed X11:6
6007/tcp closed X11:7
6009/tcp closed X11:9
6025/tcp closed x11
6059/tcp closed X11:59
7070/tcp open   realserver

nmap udp scan report:

Not shown: 991 filtered ports
PORT     STATE         SERVICE
53/udp   open|filtered domain
67/udp   open|filtered dhcps
68/udp   open|filtered dhcpc
80/udp   open|filtered http
137/udp  open|filtered netbios-ns
514/udp  open|filtered syslog
520/udp  closed        route
1234/udp open|filtered search-agent
1434/udp open|filtered ms-sql-m

Answer 1

Question: How could I establish a connection to my computer? Or at least, how would I go saving all emails to another server

I would say you're hosed on getting into your system. Saving emails? Well may sound ridiculous but just change your public DNS MX record and point to a new VM that you can run on your laptop or other place. Of course, normal local ISPs might not allow it. It would be for catching mail only. The big issue with ISPs is the sending of mail AKA being a potential spammer.