rygel no longer upnp-discoverable

[Adam Kessel <ajkessel gmail com>]

Running rygel 0.38.3 from Ubuntu Focal. At some point (perhaps since a 
recent Ubuntu upgrade although it may have disappeared earlier) rygel 
stopped being discoverable on my LAN. I can't find it with a PS3 or VLC 
running on various LAN devices no matter what the operating system is.

netstat shows rygel is listening:

tcp        0      0 192.168.98.2:36621 0.0.0.0:*               
LISTEN      597390/rygel
tcp        0      0 127.0.0.1:37751 0.0.0.0:*               LISTEN      
597390/rygel

I've whitelisted my entire LAN in iptables:

Chain INPUT (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  192.168.98.0/24      0.0.0.0/0
LOCALINPUT  all  --  0.0.0.0/0            0.0.0.0/0
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0

...

Chain OUTPUT (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  0.0.0.0/0            192.168.98.0/24
LOCALOUTPUT  all  --  0.0.0.0/0            0.0.0.0/0

I have rygel.conf set to allow discovery and listening to the right 
interfaces:

upnp-enabled=true
interface=192.168.98.0;127.0.0.0;enp0s25
port=0

I've also tried manually specifying the port or using dynamic 
configuration for the interface.

No matter what I do, the device just never appears for any client.

If I direct a web browser at the URL found by gssdp-discover, I do see 
rygel listening (e.g. 
http://192.168.98.2:36421/c9df41f0-3849-45f7-aac3-af6ea0f95941.xml ) -- 
i.e. shows the rygel xml file. 
http://adam.rosi-kessel.org/bugs/rygel/2020-05-21-rygel.xml

I've posted a debug trace from a sample run at 
http://adam.rosi-kessel.org/bugs/rygel/2020-05-21-rygel.log

Any suggestions for how to troubleshoot?