Here I will now share a modified map of "battle of the tiber" scenario.  I call it "rome with crossing". Water depth is modified so that ships have more movement options. Especially in the swamp area. Altough there first the trees need to be cut. There is also a small foot-path to cross the tiber river in the middle of the map.  In the beginning only merchants and fisher can pass, when trees cleared all ships. Merchantman can travel almost up to Vai while military ships only half the way. There are also lot of treasures all over the map but also to give rome a boost in the start, because they start with no units unlike other parties having a small group of champs. The screenshot shows a arrow ship in the swamp surrounded with worker units.  Rome-with-Crossing9.xml Rome-with-Crossing9.pmp

Seems like a bug to me. And I wonder how many other mod options have this issue.

Okey, I found the reason..... some time ago, I tested Mod Gui.... and disabled eye candy features.  It seems this option is still active when mod is disabled. I need to activate autociv and Mod-Gui [0.28.18] to have the option back in the menu, and with enabling eye candy features the waterfalls are back again. ( Well I have not seen this setting left back in user.cfg)  I did not have this in mind because I thought with disabling these mods I can eliminate this reason.

@Sundiata trying to inbox you about an artwork of Amanirenas I'm looking for but my account may be too new

This really points to the work network or router rather than the game itself. UDP traffic being blocked would explain why some players can connect while others cannot, especially since it only happened at work.