I have been having a bunch of problems with lockups and taking forever to get matches in Iron Banner multiplayer on my Xbox series S.
Looked through my settings a bunch of times, nothing seemed wrong.
Hidden EIGHT layers deep in settings (follow path below). Is a setting to allow cross-play game matches! My family setting were set to custom for some past problems in another game or something....
Path to this setting:
Settings / General / Online Safety & Family / Privacy & Safety / Xbox Privacy /
Then (if you are set to "Custom" ):
NOTE: I haven't checked but I expect checking [Adult Default] at this stage will also solve the problem if you are not running custom setting as I am.
View Details & Customize / Communication & Multiplayer /
At which point you can FINALLY change:
You Can Join Cross-Network Play: ALLOW
Solved all the 'weird' problems i was having...
Pfft... 8 layers deep in Xbox Settings were we wouldn't think to look!
Hope this helps others.
Addendum: Still (as of early morning Sept 2) - having occasional lock ups at end of match. Bungie's Hot-Fix might improve that though...