Not sure there’s much to suggest beyond “check networking & firewalls on the Pi and on your router”
The output of ip route and ip route get to 206.253.81.28 may be informative.
e.g. this is what it looks like here:
pi@piaware:~ $ ip route
default via 192.168.1.1 dev eth0 proto dhcp src 192.168.1.105 metric 202
192.168.1.0/24 dev eth0 proto dhcp scope link src 192.168.1.105 metric 202
pi@piaware:~ $ ip route get to 206.253.81.28
206.253.81.28 via 192.168.1.1 dev eth0 src 192.168.1.105 uid 1000
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