I have fifteen Cryptocurrency Wallets constantly running on one of my computers, Everything worked well, recently I added few more coins and all wallets have got synchronization issues (not syncing). I shut down several of them and things got working again. I tested that it is wallet independent problem, closing any of them solves problem, but I have to run all wallets constantly.
I am using windows 7, 64 bit, RAM 8 gb, only 50% of Ram and 10% of CPU is used in average. My Internet speed: 4 Mb Download, 0.25 Upload. My traffic (checked by freemeter) ~ 0.2 Mb Download 0.05 Mb Upload.
Can someone suggest what might be a problem?