Secure Yealink - stability?

[blind_oracle]

2. Yes, Asterisk PBX sends OPTIONS requests to the phone from time to time (every 60 sec) to check if it's alive.
When using TLS, the phone fails to respond this request in time, so the PBX marks it as UNREACHABLE.
How often is visible from the logs in my initial message - it is marked UNREACHABLE every several minutes.

When using UDP this problem does not occur - we have around 300 phones (95% of them are T22P) and they work fine through UDP.
I'm testing on two phones T22P with different firmware (as stated in my initial message), both have the issue.

If i disable phone testing on PBX (qualify=no in sip.conf) the phone is marked UNMONITORED, and the problem still persists - it cannot send or receive calls or does this very slowly.
Sometimes when i hang up caller's phone the phone that i am calling (with TLS enabled) is still ringing anyway.

3. When using HTTP (without TLS) it boots very quickly, so the network is not involed, as does not HTTPS server - it's very resourceful and can serve a lot of clients. Other HTTPS clients show normal speed, just Yealink phones are slow.

I've sent you an email through forum with requested files.