paulbates

There are a few potential trip wires
If you can "hold your breath" till you get the new plm, I would do that and not reconnect the old isy... You have to reprogram all insteon devices (restore plm) to your old isy, and then turn around and do it again for the eisy when the new plm arrives When you get the new plm, my suggestion is to restore your eisy to the last eisy back before you had plm problems, so you didn't restore bad insteon data to the new plm

Here's a screen shot of all of the values it provides
https://forum.universal-devices.com/topic/43016-if-day-of-month-x/?do=findComment&comment=379456
 

Since it programs can be accessed in UDM and working... to me it points to the java installation on the computer.  Do you have a lot of programs and variables. This is an older recommendation for t something that has the appearances of a memory problem

Java runtime memory (when Admin Console is very slow to respond)
-      If the admin console is slow to respond, it is likely you need to increase the amount of memory allocated to the Java runtime (JRE).
-      Open the Java Control Panel, select Java tab, press View button, then add or modify the Runtime Parameter -Xmx to the following:
o   -Xmx512m
-      Press Ok to close the window, then Press Apply to save the changes

The ISY's use of the network is very limited (doesn't stream) and only connects at 100mb, so an ET / WIFI bridge should work fine. Like most things network, you'll get what you pay for, eg get a highly rated product vs cheapest. 
Other ideas:
If he has some kind of cable service providing streaming services to his tv vs logging the tv in directly, the boxes providing the streaming to the tv sometimes have ET ports in the back
  I usually have my previous router hanging around after I upgrade. Some routers can be configured in bridge mode: You log the router into the campus wifi, and plug the ISY in to one of its ET ports.

The event viewer, set to level 3, is different than the log and will show detailed Insteon traffic (or lack of it) to help figure out what's going on.
Tools->Diagnostics->Event Viewer ... set to level 3 at the bottom and repeat your tests, post that back here by Saving the Log to File with a description of what part you were doing each test
Did you try the "restore device" on one of the problem devices?

I would pull the plug on the eisy, plug back in

Too much "on time" or bad links could explain some of this. Just to clarify, the UDM app gets different results than the iox console and programs?
There's limited things that can be done:
You might have done this, but pull the air gap out, count to 10 and push back in to restart it If that doesn't do it, factory resetting the kpl and restore device which will replace the links table. I don't have any KPLs at this house but had them for a long time at my prior house and either air-gapping or  occasionally factory resetting and restoring helped. 

It's a climate type, and uses status:

Put one of them in linking mode, right click on it in AC and pick restore device. It's possible things got confused in the upgrade. If that works, continue on to the others that aren't workinkg

Me too. I don't have the distance requirement, but I have 4 temp / humid sensors buried in metal / stainless fridge/freezers and they work and show strong signals.
Like any technology, its been a learning curve to get yolink's way of thinking (like how long between temp/humdity update), but everything's working
I'm getting there. It is a great compliment to an Insteon power line solution.. they both do a great job of what the other doesn't
Yes... or learning to drive stick shift all over again 🤪😂

Unfortunately you are the victim of bad timing. On of the underlying pg3x support libraries changed (MQTT) and caused  new installs of of plugins to break. I see MQTT error messages in your error log above.
UDI will work to restore it tomorrow, read this thread
 

You can also simply right click and "copy" the entire program and then rename it and "remove" the if and replace it with what you want

Before giving the PLM an "all clear", how old is it. To complete your list of things, I would unplug it, wait 10 seconds and replug in, re-run your tests.

It was me, not UDI. I was writing a program that resulted in a tight loop with many UDM push notifications.
My bad and apologies to UDI and this community
Paul

The reason it's happening is that you want to know if either is triggering, and they both are at slightly different times. 
Assuming they're both triggering within 5 minutes of each other, I would do it with a timer and a second program
Program freeze warning 1
If 
    Your first weather condition
     Or Your second weather conditon
Then
     Run program freeze warning 2
else
 
Program freeze warning 2
(no if)

Then
       wait 5 minutes
       Send notification 'xxx'
       Resource 'Freeze warning message'
else
 
When the second conditions triggers, the second program will restart because it's waiting, and you'll get only one message. Start with 5 minutes and then try reducing the wait time so there's not as much wait, but the program continues to run only once
 

It's a feature that was more important in the early ISY product days. The ISY has a web server in it and can serve up web pages, including web pages to control ISY devices and programs. HTML role has options for how much of that control you want to give a web user of your ISY.
I don't believe it has relevance in the era of plugins and mobile apps. It does not affect the Admin Console. FWIW I leave mine on advanced on the outside chance something happens and I have no other way to reach my ISY. 
From the ISY 26/99 wiki:
HTML Role:
Read Only - Allows Program status to be read. Basic - Allows Programs to be Run (If), Run Then, Run Else, and Stopped. Advanced - Allows the user to Enable/Disable Programs. Admin - Allows the user to Enable/Disable Run at Startup for Programs.  

No. It's not designed to run continuously.

I've recently purchased and installed it on the version prior to 5.8 and it installed as it should and working.
So I'm going literally by the steps you listed, I don't see that you did the install step? That would explain the outcome. Install and reboot
If that's not it, I would go to the pg3x log, set for debug and look at the entries near the bottom for errors related to yolink.

You can do it by storing one of the devices temperature's in a state variable in a program:
If
  Device_Node_Temp not equal State_Var_Temp
Then
  State_Var_Temp = Device_Node_Temp
 
The you can create the program to control the wine cellar by comparing the other device node temperature reading with the variable with the temp variable. There's a tiny arrow head at the end of the line when building the if statement next to the device node you've picked... click it and a list of variables will come up. 
It has to be a state variable for the if statement to function

It should be possible... Use the "schedule" clauses with AND and the other device conditions.
It's hard to be more specific without more info or a sample program you might have started

This is not exactly what you're asking, but there are other ways to debug
Put notifications in key spots in programs to alert you and then remove them once the program is working. I've recently completed several programs and notifications got me around my "bugs"
  As an alternative to notifications, set a variable, If your program is setting variables this is a good method and also recently used this method. To see these changes, open the event viewer (as opposed to the log) and look for entries something like VAR[ 2 7]... where 2 = state variable, and 7= variable number on the list of variables.
   

Looks like you're on an isy 994i. The new insteon i3 devices are not (fully) supported, you'll need a polisy or eisy to fully utilize i3 devices

The combination of older PLM and flaky behavior says it's time to get a new PLM and handle the swap on your terms, not when things get a lot worse and it stops working.
 

Also possible-to-likely is that the new router's ip4 subnet is different than the old router's.
Via the mobile app:
Settings Systems Pick your isy Scroll down to "local connection settings" Your ip and ports will be listed there