iTunes wi-fi sync not working

So there is a mystery story with synchronization over wi-fi.

I've been synchronizing over wi-fi my macbook and iPhone for about 3 months. But some day it happened to stop working. iTunes doesn't see iPhone over wi-fi anymore. Checkbox is checked. Also, handoff stopped working(any app).

I've discovered that if I connect to another wi-fi network my phone is shown and able to synchronize over wi-fi(returning to main router changes things back).

Both devices are connected to the same network (it's the only one I have nearby) and bluetooth is on both on mac and phone.

I've tried:

• reset network and location settings
• full reset phone and backup then
• restoring wi-fi router
• switching off and on wi-fi and bluetooth
• loggin out and in Apple ID, iTunes etc.
• unchecking/checking handoff and iTunes wi-fi sync
• delete wi-fi network

Nothing has worked for me. The only clue I have - it's something with wi-fi, though I don't change anything there and restored to default.

I checked the Apple forums and several people say they fixed it by plugging iPhone into MB, it asked if to trust the device on the MB and the iPhone. When trust on both is selected, it synced on the cable and now wifi sync is back to normal. May be this workaround will do the thing?

Also do you think Firewall can be an issue?

Or Apple Mobile Device Helper process could be the bump, you can just force quit that process through Activity monitor