XRS4500 delay LiveTV changing channel/stream

I've got 2 supposedly identical XRS4500 (purchased as a pair, configured to play out of the box, IPTV link set) on the same wifi network. Both use the remote with keyboard on the back side and USB dongle in the box. One box switches LiveTV channel/stream almost instantly, less than 1 second. The other (mine of course, LOL) has a delay of at least 5 seconds, sometimes 10 or 15. On the slow box, the stream's ID banner switches to the new stream instantly with the old stream's image frozen and no audio. After several seconds there is a blip of sound, silence for a second, then the video and audio of the new stream appears.

Version 4.0.524 updated 1/18/2022. Symptom unchanged by update.
Response in VOD is the same on both boxes.

I've tried swapping boxes between TV's - the symptom follow the box
I've set up the two boxes with two TVs and trolled through all settings and preferences side by side.
Used the multiple click on <home> button to close any open apps, That did originally show 4 or 5 closed for several instances, now routinely 0.
Occasionally have a freeze responding to remote control with a pop-up with options to close the app (which one???) or wait. Often the system recovers on it's own before I respond the the pop-up.

I'd appreciate any suggestions to try. TIA

Regards
RDL

try to clear cache and guide and try again.

Did both. No change. Then did restart, just in case that needed for changes to take effect. Again no change.
Thanks for the suggestions though

Regards
RDL

try to delete server and try adding again and see if that helps. if not then two options.
1. update to newest beta 5 software
2. factory reset.

Have to think about that LOL.
I'm an absolute newbie on IPTV including BuzzTV. I'm leery that I'll mess up and wind up with nothing.
OTOH, I suspect you're correct about my options. Do you know if it's possible to retreat to 4 if beta 5 misbehaves?

Regards
RDL

no you won't be able to downgrade once you update to buzz 5. if you ever decide to update make sure to read log before you update. also, make a back up for you box before you factory reset just incase.

hit the home button twice quickly That will close running apps

If it means anything, an update regards a comment/symptom in my first post:
"Occasionally have a freeze responding to remote control with a pop-up with options to close the app (which one???) or wait. Often the system recovers on it's own before I respond the the pop-up."

The app heading the pop-up is Buzz TV 4.