L26500 IP connectivity weirdness - can't connect but can

Our 26500 had been running fine for quite a while.
Today the RIP stopped. (Onyx PH 12)
Reloaded the RIP, and reinstalled the printer inst file.
The RIP queue is happy, but on configuration, it cannot connect with the printer when you click 'test'.
However if I open up a web browser (Firefox) I can connect with the printer's embedded web server to look at ink levels, accounting , etc.

If I send a file to print, the RIP cancels it saying it was cancelled at the console, which it was not.
The console is happy, and awaiting a file.
The RIP cannot connect with it. Going via an old router that worked up till 2 days ago, and still seems to work for accessing the embedded web server.

I have not changed the IP address.

I'd appreciate any ideas, thanks.

 

Thanks for taking the time to reply.
I solved it by reinstalling the printer inst file, and selecting L260, instead of L26500, and it was happy.
But previously, L26500 worked and 260 did not... very weird.
"Phew!"...