Remote Desktop Connection started to freeze frequently

Hello.

I'm using 2 computers for 2 types of activities for maximum separation. For convenience I use one to connect to the second using Remote desktop and this setup worked well for more than 6 months: real-time images and hours-long flawless sessions. Two-three weeks ago things changes and I in most of the time I experience screen freezes every 5 minutes or so.

Some details will follow:

• viewing computer: Win 10 Pro 64bit - I7 processor 8GB RAM, SSD; RDC Shell Version 10.0.17763
• viewed computer: Win 7 Pro 64bit, Service Pack 1 installed - Core2Duo, 4GB RAM, SSD; RDC Shell Version 6.2.9200 - Remote Desktop Protocol 8.0 supported - tried to install Windows6.1-KB2923545-x64.msu but received the message "The update is not applicable for your computer" despite the SP1 being installed.
• wired gigabit network for both routers and computers, no WiFi used for any of them, I use a repeater but any cable is 5 meters long tops

The problem can be seen a few minutes after opening the session, the screen on the viewing computer freezes and in most of the times does not recover in a few minutes; sometimes it does in ~3 minutes but I seldom have the time and patience to wait so long.

Since the second computer is meters away from me I typically try to restart the connection - here I noticed the on the viewing computer closing the app takes 2-3 seconds, it doesn't close instantaneously. In most of the times if I close and reopen within 1-2 minutes from first freeze the screen is still stuck: I can connect apparently as usual only to receive a black screen. That's the signal for me to actually walk to the second computer and simply log on, this does it and I can resume the session from my first computer for some time...minutes mostly. When I login at the second computer I noticed that at the viewing computer the image remains frozen, no sign of the changes that happened at the remote computer won't be seen for minutes...eventually after minutes the connection brakes.

I noticed this problem started recently, 2-3 weeks ago and I would like to fix this a.s.a.p.

Thank you.

---Update: I was able to update RDP to 8.1 version using KB2830477, it took some time - I restarted after each piece - but worked flawlessly. Made no difference for my problem thou...