Can't see all servers

I can see only 374 servers, but my friend on the same ISP can see 545 servers.
Any idea what is wrong?

 

It seem to be something in the game (settings or maybe new UI), because I can see all the servers via steam directly: Steam --> View --> Servers (filter by rfactor2 game).

 

I also cant see all servers (there are over 500 servers), but i can see only 53 of them. And that one i will use isnt listed.
There is a parameter at the multiplayer.json which maybe can fix the problem, i thought:
"Net Flush Threshold":472,
"Net Flush Threshold#":"threshold for auto-accumulation flush while building data chunks (default is standard MTU of 536, minus 64 bytes room for layer headers: 472)",
At my Windows 10, i can use an MTU of 1464 (Net Flush Threshold = 1400 = 1464 - 64).
rFactor changes this value (1400) to 1024, but this doesnt work or help.

 

These are all servers i can see:

 

I found the solution.
It was a wrong value at my steam client. After setting this value to 5000 i can see all servers (see pic).

 

I do not know, how the listing is implemented at rFactor, if rFactor itself would collect all the existing servers, i could be a bug at rFactor.