Can Anyone Access their LAN services such as FTP?

Hello Community, I have been struggling to get my ftp connection on my LAN. I have been with ATT support for many times and hours trying to get my internal FTP services to work properly. Every trine I am with the phone with support they perform actions that often does not make sense. I just had a call with them on 8/19 reporting this problem and what they did is assigned the FTP services (port forwarding) on my Security Camera, why? I told them that the camera connects to my FTP server on my computer so I originally set open the FTP to my server...am I missing something. long story short I need help. When I had my Comcast as ISP and my own router I was able to make this security/FTP work for 5 years. When I replaced it with ATT internet/equipment it all stopped. So far I already performed the following:

1. Firewall Settings opened FTP port 21

2. Opened port 88,888,8150 to access camera remote/WAN - Success

3. Factory Defaulted my router per ATT - that was a hasle but still it did not work

4. ATT Support assigned FTP services on my Camera?????? don't know why? ATT support never called me back after he rebooted my router.

5. Put my Camera and My FTP server on DMZ plus.... did not work and it is not recommended to put server on DMZ+

Its been 2 weeks since I moved to ATT internet, at this point ATT support does not know what they are doing...I also read adding a router, but that is the least thing I would like to do....PLEASE HELP...thank you