The only way to connect to peers is through a DGRAM unix socket?

Question

I'm running an experimental setup. I have Ubuntu on my desktop computer with a USB hub connected and a 1TB ssd sata drive mounted to it at /mnt/d1

I'm using a second docker instance

dockerd -H unix:///var/run/docker1.sock -p /var/run/docker1.pid --ip-masq=true --bridge=docker1 --data-root=/mnt/d1/docker-data --exec-root=/mnt/d1/docker-exec
dockerd -H unix:///var/run/docker1.sock run -itd --network=host --privileged --hostname test --user root --name test 20:latest
dockerd -H unix:///var/run/docker1.sock exec --user root -it 18 /bin/bash
# installed bitcoind here

Next I set up my custom datadir in /home/BTC where I write in my bitcoin.conf the normal bitcoin port and rpc port

rpcuser=redacted
rpcpassword=redacted
port=8333
rpcport=8332
listen=1
datadir=/home/BTC

When I start Bitcoind like bitcoind -datadir=/home/BTC it is unable to get any connections and I see in debug.log

Bound to [::]:11235
Bound to 0.0.0.0:11235

Long-story-short; I tried putting the port out of range 999999999999999 then ran bitcoind again

Bound to [::]:25177
Bound to 0.0.0.0:25177

So now it has connections and gets blocks but I am confused as to what happened.

netstat -anp | grep "25177"
  unix 3 [ ] DGRAM CONNECTED 25177 1/init
netstat -anp | grep "DGRAM" | grep "1/init"
unix  4      [ ]         DGRAM      CONNECTED     16138    1/init               /run/systemd/notify
unix  2      [ ]         DGRAM                    22988    1/init               /run/systemd/journal/syslog
unix  24     [ ]         DGRAM      CONNECTED     22997    1/init               /run/systemd/journal/dev-log
unix  8      [ ]         DGRAM      CONNECTED     22999    1/init               /run/systemd/journal/socket
unix  3      [ ]         DGRAM      CONNECTED     33808    1/init               
unix  3      [ ]         DGRAM      CONNECTED     25176    1/init               
unix  3      [ ]         DGRAM      CONNECTED     16139    1/init               
unix  3      [ ]         DGRAM      CONNECTED     16140    1/init               
unix  3      [ ]         DGRAM      CONNECTED     25177    1/init               
unix  3      [ ]         DGRAM      CONNECTED     33807    1/init               
unix  2      [ ]         DGRAM      CONNECTED     25779    1/init

Somehow it connected through! how would I reproduce one of these DGRAM unix sockets to let it through on port 8333?