Nether portals in my Realm no longer link to their matches in the Nether. We had a working Nether hub until 1.11.4.

Overworld portals still link to the appropriate portal in the Nether, but when using ANY portal located in the Nether players come out of the first Nether portal built on the Realm. This is accompanied by the message, "You have been teleported to 8290.50, 65.00, 19762.50". There is one time that it teleported me to the world spawn (all items and xp were retained and no death screen, just went through a portal in the Nether and came out at world spawn where there is NO Nether portal).

None of the Command Blocks in the Realm are set up to teleport characters to the coordinates mentioned in the above quoted message.

The original portals were broken and remade, new portals were made in other locations and properly placed to link up, but the issue persists.

Distance from the original Overworld portal does not seem to be a factor, as portals a couple thousand blocks away still link to it.

A mod can join the Realm if they want to see for themselves without having to use a testing world to recreate the issue.