I have a strange issue with new Winboxes (not only newest I think), I can`t connect to the older devices with some older RoS via L2...I tried connect...I can see 3 dots logining in and then disconnecting. E.g. I was with the customer today and there is one CRS switch (1xx) with IP 0.0.0.0.
I wanted to fix its IP but I can`t connect via L2 with my 2 newest Winbox versions.
Is there any issue with older RoS and newer Winbox versions?

I'm not sure about L2, but there have been some breaking changes with L3. Very old RouterOS (5.x and older) is not supported for about two years. And I think 6.43 and newer doesn't work by default either, but you can enable Tools->Legacy Mode if you need it. I guess L2 should be similar.

I already known it, of course I try to set up legacy mode too. No change.
I`ll be with the customer on Monday but I`m afraid I have to be reset to the default his switch because I have no way how can I log in with 0.0.0.0 IP.
I always tried mac telnet from another MTs in the network but I can`t connect too.

How about downloading an old version of winbox? There's a forum topic about that.

If it's something ancient, last WinBox version that will work is 3.12.

I`ve found the way...I have to connect twice...after 1st disconnecting when I use reconnect I`m able to login correctly.

Had same issue when I factory reset a customer of mines router, what resolved it was to add static IP address on my laptop (usually on DHCP)