[44net] Help troubleshooting AXIP link

Hello 44Net. I'm looking for some help from those who have experience! I have recently set up my first AXIP link through the 44Net, but I'm having trouble connecting to my AXIP partner. My IP is 44.135.88.200 and my partner is 44.135.32.201 So far I can TELNET and PING back and forth from ANY 44 node, yet all attempts to make a AX25 connection to my AXIP partner fail. I can TELNET/PING from my partner to my node okay. I can TELNET/PING to my partner from my node okay. I can PING the 44 gateway without issue. I have also been broadcasting my NODES table to my partner. My partner does not seem to "hear" my CONN REQ's or NODES broadcasts. My partner is also broadcasting his NODES table to me. I am not hearing his broadcasts. Using TCPDUMP and WIRESHARK, I can see the traffic going out my tunnel to my regional gateway. I have tried to capture AX25 packets FROM my partner ... nothing heard. I have been able to capture AX25 packets TO my partner ... all looks correct. I have been able to capture packets when TELNETing or PINGing. TRACEROUTEs to my partner work fine (2 hops). My situation is a little more complex because I am not going direct to the UCSD gateway. Instead, I am sending all my 44Net traffic through my regional gateway (44.135.88.252). It has been suggested that my ISP may be "source filtering", but i have no way of verifying that. I am running both my router and node on a Raspberry Pi (I know ... plug your nose!  LOL) I am using IPTABLES, which I have disabled for testing to see if it was interfering (it wasn't). My router/node is behind a CPE router, and is in the DMZ. I have several AX-UDP ports working fine. So here are my questions: Does it sound like I am suffering from source filtering? How can I verify whether my ISP is source filtering? What have I overlooked in my troubleshooting? What would you suggest as my next step? Any and all suggestions are welcome. I'm going bald quickly pulling out my hair! Thanks in advance, Matt VE3OY (FN03gq) Toronto, Canada -- /My mind is like a web browser. 27 tabs are open, 9 aren't responding, lots of pop-ups...and where is that annoying music coming from?/