The errors there are things that you might want to fix, the invalid DH group indicates that the client is trying to connect with a security set that the MX does not support, it might then simply be failing back to one that it does, or it might cause a pause in communications.
Having said that we (like most companies) have the same change in working practices as you have and also the same issues.
I started with a wireless connection and had loads of slowdown and disconnection issues, Outlook disconnecting and not reconnecting, file copy issues, slow application access etc. I found out by chance that these issues were 95% related to an incompatibility between my home (Meraki MR55) WiFi and the WiFi chip in my work laptop (Intel 8260) as when I tried a wired connection at home it was much better. I then found that it was only when the laptop was on battery power that the serious issues occurred and by disabling the chipset's power saving features it was almost perfect. Since then I changed the wireless card to an AX200 and it works perfectly (for wireless), there are still minor issues and those are mostly resolved by using the wired connection.
The next thing I tried was using a spare MX64 that we had as an extension to the corporate SD-WAN by connecting it to the main hub in the datacenter as a spoke; with that setup I haven't had any issues at all in over 3 weeks. The connection I have is an FTTC home package with 55Mbps download and 10Mbps upload, so nothing expensive.
Having assisted many of our other users with their home issues their connections are variably affected by all the above and a number are crippled by having ADSL lines with <10Mbps download and <1Mbps upload. The only way in my opinion that you are going to get something half decent on that connection is to use Citrix/Terminal Services or a VDI setup.
