Issue after upgraded from ubuntu 18.04 LTS to latest ubuntu 20.04 LTS where extra monitor blanking out for few seconds randomly

can someone help please urgently as it is disturbing my work from home setup?

It worked fine in Ubuntu 18.04 LTS but issue in 20.04 LTS.
Extra monitor- (philips 273V7QDAB)
Laptop – Inspiron 15R 5000

I also tried to google and tried few bits like disabling DPMS on X. I changed HDMI cable. I dont see any additional drivers to be installed in updates. System is fully upto date. I ran out of options. Please see below output:

DISPLAY driver details:

# lspci -nn | grep VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M] [1002:6601]

---- 
#lshw -c video

*-display                 
       description: VGA compatible controller
       product: Mars [Radeon HD 8730M]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:01:00.0
       version: 00
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
       configuration: driver=radeon latency=0
       resources: irq:33 memory:a0000000-afffffff memory:c0000000-c003ffff ioport:3000(size=256) memory:c0040000-c005ffff
*-display
       description: VGA compatible controller
       product: 3rd Gen Core processor Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:32 memory:c1000000-c13fffff memory:b0000000-bfffffff ioport:4000(size=64) memory:c0000-dffff

Thanks, Rajesh